- Providers signed up to the Ofcom speeds code give a minimum guaranteed speed at the point of sale.
- If speed falls persistently below the minimum and is not fixed in time, a right to exit can apply.
- Wired speed tests at different times provide the evidence a speed complaint needs.
- A complaint goes to the provider first, then to alternative dispute resolution if unresolved.
- After deadlock or eight weeks, an approved scheme such as CISAS can issue a binding decision.
Check your minimum guaranteed speed, log wired speed tests as evidence, and complain to the provider first. If unresolved after deadlock or eight weeks, an approved scheme such as CISAS can rule on the case.
Last reviewed: June 2026
Start with your guaranteed speed
The starting point for any speed complaint is the minimum guaranteed speed the provider gave at the point of sale. Providers signed up to the relevant Ofcom code of practice must provide a personalised minimum guaranteed download speed before a contract begins, based on the line to the specific address. This figure, rather than the advertised headline speed, is the benchmark a complaint is measured against. Finding it, usually in the contract or order documents, is the first step, because a complaint is far stronger when it shows the connection falling below the guaranteed minimum rather than simply below the advertised speed.
If the speed is below the advertised figure but still above the guaranteed minimum, the position is weaker, because the guarantee is the contractual commitment. Knowing where the connection sits relative to the guaranteed minimum shapes the whole complaint.
Gather the evidence
A speed complaint is only as strong as its evidence. The most useful evidence is a series of wired speed tests, taken with a device connected to the router by ethernet, with other activity paused, at different times of day including busy evening periods. This removes WiFi and household activity as variables and shows the line's true performance. Recording each test with the date, time, method and result builds a clear picture of whether the connection consistently falls below the guaranteed minimum. A single low reading is easy to dismiss, while a consistent record under good conditions is compelling.
| Step | Action | Purpose |
|---|---|---|
| 1. Check the guarantee | Find the minimum guaranteed speed | Sets the benchmark |
| 2. Gather evidence | Wired tests at different times | Proves the shortfall |
| 3. Rule out the home | Test wired, check wiring and device | Confirms a line issue |
| 4. Complain to provider | Report with evidence | Gives a chance to fix |
| 5. Escalate | Dispute resolution after deadlock or 8 weeks | Independent binding decision |
Rule out in-home causes
Before complaining, it is worth confirming the problem lies with the line rather than the home setup, because a provider will check this too. Testing wired rather than over WiFi is essential, since WiFi limits are not the provider's responsibility. Checking that the router is connected at the master socket, that internal wiring is sound, and that the device is capable, rules out common in-home causes. If a wired test from the router still falls below the guaranteed minimum, the issue points to the line or network, which is the provider's responsibility and the proper basis for a complaint.
Make the complaint to your provider
The first formal step is to complain to the provider, which must be given the chance to resolve the issue. Setting out the problem clearly, with the guaranteed minimum speed and the evidence of wired tests, gives the provider what it needs to investigate. The provider may test the line, send an engineer, or make changes to try to improve the speed. Under the speeds code, it has a set period to bring the speed up to the guaranteed minimum. Keeping a record of the complaint, including dates and what was said, is important for any later escalation.
The right to exit
A key protection is the right to exit. Under the Ofcom speeds code, if a signed-up provider cannot bring the speed up to the guaranteed minimum within the set period, the customer gains the right to exit the contract without penalty, often including any phone and television services bought with it. This is a powerful remedy, because it frees the customer to move to an alternative without an early termination charge. Invoking it requires having gone through the provider's process and given it the chance to fix the problem first, which is why following the steps in order matters.
Escalating to dispute resolution
If the complaint cannot be resolved with the provider, the next stage is alternative dispute resolution. Where the provider issues a deadlock letter, or where the complaint remains unresolved after eight weeks, the customer can refer it to the approved dispute resolution scheme the provider belongs to. The main schemes are CISAS and the Communications Ombudsman, and a provider belongs to one of them. These schemes are independent and can issue a binding decision, including remedies. The referral is free to the customer, and it provides a route to an independent ruling when the provider and customer cannot agree.
What the schemes can do
An approved dispute resolution scheme reviews the evidence from both sides and can make a binding decision. Depending on the case, it can require the provider to take action, to allow the customer to exit, or to provide a remedy such as compensation or a goodwill payment. The scheme's decision is binding on the provider if the customer accepts it. This independent backstop is what gives the complaint process its teeth, because it means a provider cannot simply ignore a valid complaint indefinitely. Ofcom approves these schemes but does not itself rule on individual consumer complaints.
Putting it all together
In summary, an effective speed complaint follows a clear order: check the guaranteed minimum speed, gather wired test evidence at different times, rule out in-home causes, complain to the provider and give it the chance to fix the problem, and escalate to the approved dispute resolution scheme after deadlock or eight weeks if it is not resolved. The right to exit provides a strong remedy where the guaranteed minimum is not met. Following these steps, with good evidence and records, gives the best chance of a fair outcome.
Frequently Asked Questions
What is a minimum guaranteed speed?
It is a personalised minimum download speed that a provider signed up to the Ofcom speeds code gives at the point of sale, based on the line to the specific address. It is the contractual benchmark a speed complaint is measured against, rather than the advertised headline speed, and falling persistently below it can trigger a right to exit.
How do I prove my broadband is not meeting its minimum speed?
The strongest evidence is a series of wired speed tests, taken with a device connected to the router by ethernet, with other activity paused, at different times including busy evenings. Recording each with the date, time, method and result builds a clear picture. A consistent record under good conditions is far more compelling than a single low reading.
When can I exit my contract because of slow speed?
Under the Ofcom speeds code, if a signed-up provider cannot bring the speed up to the guaranteed minimum within the set period after being given the chance to fix it, the customer gains the right to exit without penalty, often including phone and television services bought with it. Following the provider's process first is required.
What is CISAS?
CISAS is one of the approved alternative dispute resolution schemes for communications complaints, alongside the Communications Ombudsman. A provider belongs to one of them. After a deadlock letter or eight weeks without resolution, a customer can refer a complaint to the relevant scheme, which is independent and can issue a binding decision.
How long does a broadband complaint take?
It varies. The provider should be given the chance to resolve it first, and the speeds code sets a period to bring speed up to the guaranteed minimum. If unresolved, a customer can go to dispute resolution after a deadlock letter or eight weeks. The dispute resolution scheme then reviews the case and issues a decision, which takes further time.
Does the complaint need to be about the guaranteed speed specifically?
A complaint is strongest when it shows the connection falling below the personalised guaranteed minimum, as that is the contractual commitment. A connection below the advertised speed but above the guaranteed minimum is a weaker position. Knowing where the connection sits relative to the guarantee shapes how the complaint is framed.
