TL;DR
- Raise a formal complaint with your operator first; keep a written record of every contact.
- Operators are required by Ofcom to acknowledge complaints promptly and provide a final response within eight weeks.
- A deadlock letter or the expiry of eight weeks without resolution unlocks access to an Ofcom-approved Alternative Dispute Resolution (ADR) scheme.
- UK mobile operators are members of either CISAS or the Communications Ombudsman; both are free for consumers.
- ADR decisions can result in compensation, a service fix, or a contract remedy — and are binding on the operator if accepted.
The regulated complaints framework
Ofcom sets the complaint-handling rules for UK communications providers under the General Conditions of Entitlement, which all licensed operators must follow. Condition C4 requires providers to operate an accessible, transparent complaints procedure, publish information about it clearly, and signpost customers to an approved ADR scheme when a complaint cannot be resolved internally. This means the framework is not voluntary — every mobile network operating in the UK is legally obliged to participate.
The two Ofcom-approved ADR schemes for mobile are CISAS (Communications and Internet Services Adjudication Scheme), operated by the Centre for Effective Dispute Resolution (CEDR), and the Communications Ombudsman. Which scheme applies depends on which one your operator has joined; the operator is required to tell you which scheme covers your dispute. Both operate independently of the industry and cannot charge consumers to make a complaint.
Stage one: raising a formal complaint with the operator
The process begins with a formal complaint to the operator itself. Many disputes are resolved at this stage without escalation. A formal complaint is distinct from a general customer service enquiry; you should use the word “complaint” explicitly, as this triggers the operator’s regulated obligations. Complaints can typically be submitted in writing (email, web form, or letter), by phone, or in-store. Writing is strongly preferable because it creates a dated, retrievable record.
At the point of complaint, note the reference number given to you, the name or ID of any agent you spoke to, the date, and the substance of what was said or agreed. Ofcom guidance recommends keeping a complaint diary. You should be specific: state the problem, the remedy you are seeking, and any financial loss or inconvenience caused. Vague complaints take longer to resolve and give less material for an ADR adjudicator should the case escalate.
What the operator must do and when
Under the General Conditions, operators must acknowledge a complaint promptly. They then have a maximum of eight weeks to issue a final written response — commonly called a “final position letter” — that either resolves the matter or explains the operator’s final stance. The eight-week clock typically runs from the date your complaint was received by the operator’s complaints team, not from when you first contacted customer services. If you are unclear when the formal complaint was logged, ask in writing and keep the reply.
During those eight weeks the operator should investigate the issue, communicate progress, and make reasonable attempts at resolution. If the matter is resolved to your satisfaction at any point in this window, no further escalation is needed. However, if you reach either of the two gateway conditions — a deadlock letter or the expiry of eight weeks — without a satisfactory outcome, you are entitled to take the dispute to ADR.
| Stage | What happens | Timeline | Gateway to next stage? |
|---|---|---|---|
| 1. Informal contact | Customer service call or chat | Immediate | No — use word “complaint” to escalate |
| 2. Formal complaint lodged | Operator acknowledges; 8-week clock starts | Day 0 | Yes — starts regulated timeline |
| 3. Operator investigation | Operator reviews, may offer remedy | Up to 8 weeks | Deadlock letter or 8 weeks = gateway |
| 4. Deadlock / 8-week expiry | Positions confirmed irreconcilable or time elapsed | Anytime after Day 0 | Yes — ADR access opens |
| 5. ADR (CISAS / Ombudsman) | Independent adjudication; written submissions | Typically 4–12 weeks | Decision binding on operator if accepted |
| 6. Ofcom / courts | Regulatory enforcement or civil claim | Variable | Last resort; separate from ADR |
Understanding the deadlock letter
A deadlock letter is a written statement from the operator confirming that both parties have reached an impasse — the operator has made its final offer or position and cannot go further. It is a formal document that explicitly opens the door to ADR. Operators are not required to issue a deadlock letter spontaneously; you can request one at any point after the complaint has been lodged, though in practice it is most useful once negotiations have stalled and you believe the operator will not improve its offer. Keep the deadlock letter carefully; it will be required when submitting an ADR application.
If an operator fails to issue a deadlock letter or issue a final response within eight weeks, you do not need to wait indefinitely. The eight-week rule is itself a gateway: once that period has elapsed without a satisfactory resolution, you may go directly to the relevant ADR scheme. Document the date the complaint was formally lodged so the timeline is clear in any submission.
The ADR schemes: CISAS and the Communications Ombudsman
CISAS handles disputes for some of the UK’s larger network operators and MVNOs. The Communications Ombudsman covers others. The schemes are distinct organisations but both operate under Ofcom approval and must meet Ofcom’s criteria for independence, effectiveness, and accessibility. Consumers pay nothing to use either scheme. Applications are typically made online and require a summary of the dispute, supporting documents, and the deadlock letter or evidence the eight-week period has elapsed.
Both schemes operate through written submissions rather than oral hearings; you submit evidence by a deadline and the adjudicator considers all material before issuing a decision. Decisions can require the operator to pay compensation, provide a service remedy, or cancel a contract. Operators are contractually bound to comply with a decision if the consumer accepts it. If you reject the decision you are free to pursue other routes such as the courts, though this is comparatively rare for mobile disputes.
What to document throughout the process
Evidence quality is frequently decisive in ADR outcomes. Useful documentation includes: screenshots or printed copies of bills, account portal pages, or promotional terms; call logs or recordings (many operators record calls and will provide transcripts on request); written exchanges including emails, web-chat transcripts, and letters; notes of telephone calls including date, time, and the name or agent ID of the person spoken to; and any written offers, credits, or commitments made during the complaint process. Store copies in a location separate from the handset or SIM in question.
Where the dispute concerns service quality such as persistent poor coverage, technical evidence helps. Ofcom’s Connected Nations report and coverage checker data can provide context, though the burden of evidencing the impact on your specific service rests with you. Speed-test results, timestamped screenshots of “no service” notifications, and dates of failed calls or data outages all strengthen a submission.
What this means in practice
Priya lives in Bristol and has been on a rolling SIM-only contract with a national operator for two years. In January 2026 she noticed a charge on her bill she did not recognise. She called customer services but the agent said the charge was correct without explanation. Priya followed up by email using the word “complaint” and was given a complaint reference number; this started the eight-week clock on 14 January. By 1 March — 46 days later — she had received two holding responses but no final position. She emailed requesting a deadlock letter. The operator issued one on 7 March, confirming it would not refund the charge. Priya submitted her complaint to the Communications Ombudsman on 10 March, attaching her original complaint email, the two holding responses, the deadlock letter, and three months of billing screenshots. The adjudicator upheld her complaint in part and directed the operator to refund the disputed charge and apply a goodwill credit. Priya accepted the decision, which the operator was then bound to implement.
Related Guides
How we verified this
This article draws on Ofcom’s General Conditions of Entitlement (in particular Condition C4 on complaint handling), Ofcom’s published guidance on ADR schemes, the CISAS and Communications Ombudsman scheme rules, and Ofcom’s annual complaints data publications. No operator-specific claims have been made.
Disclaimer: Kaeltripton.com is an independent UK editorial publisher. We are not regulated by Ofcom or the FCA and we do not sell or arrange mobile services, insurance, or financial products. This content is for general information only and is not legal, financial, or technical advice. Rules, prices, and operator policies change. Verify the current position with Ofcom, GOV.UK, the ICO, or your provider before acting. ICO registered ZC135439. Last reviewed: 2026-06-05.
Frequently Asked Questions
How do I make a formal complaint to my mobile network?
Contact the operator through its official complaints channel — email, web form, or letter is preferable to a phone call because it creates a written record. Use the word “complaint” explicitly so the operator’s regulated obligations are triggered. State the problem clearly, the remedy you want, and any financial impact. Ask for a complaint reference number and note the date. Operators are required under Ofcom’s General Conditions to acknowledge complaints and begin an investigation.
How long does a mobile operator have to resolve my complaint?
Under Ofcom’s General Conditions of Entitlement, operators have a maximum of eight weeks from the date a formal complaint is received to issue a final written response. If eight weeks pass without a satisfactory resolution, or if the operator issues a deadlock letter before that point, you may escalate to an Ofcom-approved ADR scheme — either CISAS or the Communications Ombudsman, depending on which scheme your operator has joined.
What is a deadlock letter for a mobile complaint?
A deadlock letter is a formal written statement from the operator confirming it has reached its final position and the dispute cannot be resolved internally. It acts as an official gateway to ADR; once issued, you can immediately refer the matter to CISAS or the Communications Ombudsman without waiting for the full eight-week period to elapse. You can request a deadlock letter from your operator at any point after lodging a formal complaint if you believe negotiations have stalled.
When can I go to CISAS for a mobile dispute?
You can refer a complaint to CISAS (if that is your operator’s chosen ADR scheme) once either a deadlock letter has been issued or eight weeks have passed since your formal complaint was lodged without a satisfactory resolution. CISAS is free to consumers and accepts complaints in writing. You will need to provide a summary of the dispute, supporting evidence, and either the deadlock letter or proof the eight-week period has expired.
What documentation should I keep for a mobile complaint?
Retain copies of bills and account screenshots, all written correspondence including emails and web-chat transcripts, notes of phone calls (date, time, agent name or ID, substance of conversation), any promotional or contractual terms you rely on, and the complaint reference number. If the dispute involves service quality, timestamped speed-test results and screenshots of outage notifications help. Store copies separately from the device in question in case it is lost, stolen, or reset.
