Three is the UK’s smallest of the four major mobile networks, but it has the same regulatory obligations as the others — including a requirement to operate a clear complaints process and to belong to an Ofcom-approved Alternative Dispute Resolution (ADR) scheme. For Three customers, the ADR scheme is Ombudsman Services: Communications (OSC).
This guide explains the Three UK complaints process step by step, from first contact with customer services through to escalation at OSC.
Three’s ADR Scheme: Ombudsman Services: Communications
If you have an unresolved complaint with Three after 8 weeks, or if Three issues you with a deadlock letter, you have the right to take the dispute free of charge to Ombudsman Services: Communications. Their decision is binding on Three if you accept it.
Step 1: Try Three Customer Service First
Most issues can be sorted out without going formal. Have your account number, mobile number, and the relevant bill or correspondence to hand. Contact options:
- Phone: 333 from a Three mobile (free), or 0333 338 1001 from any other phone
- Live chat: through the Three app or three.co.uk
- Twitter/X: @ThreeUKSupport
- In a Three store: stores nationwide
Take notes of every contact: date, time, advisor name, what was discussed, and any reference number. This evidence becomes important if you escalate later.
Step 2: Raise a Formal Complaint
If standard customer service cannot resolve the issue, ask explicitly to make a formal complaint. The advisor must register it and provide a complaint reference number.
Three’s formal complaint channels:
- By post: Three Customer Services, Hutchison 3G UK Limited, PO Box 333, Glasgow G2 9AG
- By email: via the form on three.co.uk → Help → Complaints
- By phone: 333 (Three mobile) or 0333 338 1001, asking for the complaints team
A written complaint creates a clean, dated record that is much harder to dispute than a phone conversation. Your written complaint should include: account number and mobile number, registered name, a clear factual summary of what happened, dates of previous contacts and what was promised, copies of evidence, the resolution you want, and a deadline (14 days is reasonable for a clear billing case).
Step 3: Wait for Three’s Response
Three has up to 8 weeks from your formal complaint to resolve the issue or send you a deadlock letter. They should:
- Acknowledge your complaint
- Investigate
- Send a written response
- Where appropriate, offer a refund, credit, contract change, or compensation
Most cases are resolved well inside the 8 weeks — the deadline matters because it is the point at which you can escalate to OSC.
Step 4: Escalate Internally
If the first response is unsatisfactory, ask for the complaint to be escalated to a senior complaints team or a manager. More senior staff have more authority to authorise refunds and goodwill credits.
Step 5: Take Your Complaint to Ombudsman Services
If 8 weeks have passed without resolution, or you have a deadlock letter from Three at any point, you can submit the dispute to Ombudsman Services: Communications free of charge.
- Submit your complaint at ombudsman-services.org or by post (PO Box 730, Warrington WA4 6WU; phone 0330 440 1614)
- OSC notifies Three, who must respond
- A case handler reviews both sides’ evidence; mediation may be attempted first
- If mediation fails, an Ombudsman makes a final, binding decision (binding on Three if you accept)
Most cases are resolved within 6–8 weeks of filing.
Common Three UK Complaints
| Problem | Likely grounds |
|---|---|
| Surprise mid-contract price increase | Ofcom GC C1 (price rises must be specified in pounds and pence at sign-up under the January 2025 rule); right to exit without ETC if not properly disclosed |
| Charged after switching away | Ofcom GC C5; demand a refund and stop the direct debit |
| Roaming charges higher than expected | Consumer Rights Act 2015; Ofcom roaming transparency rules |
| PAC code refused or delayed | Ofcom GC C4 (must send PAC within 1 minute of text request) |
| Three SIM no longer working after merger / network change | Three completed a merger with Vodafone in 2024-2025; if a network or product change has materially worsened your service, you may have grounds to exit without ETC |
Three and the Vodafone Merger
The merger between Three UK and Vodafone UK was approved by the CMA in 2024 and has been progressively combining the two networks. If a change made under the merger has materially affected the service you signed up for — for example, coverage in your area has worsened, a feature has been withdrawn, or your contract terms have changed — you may have grounds to exit your contract without paying an early termination fee. The trigger is “material detriment”: the change makes the service substantially worse than what you contracted for. Raise this in your formal complaint and reference Ofcom’s General Conditions if you believe the change was not properly notified to you.
The 14-Day Cooling-Off Period
If you signed up to a new Three contract by phone, online, or off-premises (anywhere other than in a Three store), you have 14 days from receiving the SIM/phone to cancel without penalty under the Consumer Contracts Regulations 2013. Three may charge pro-rata for usage but cannot charge an early termination fee. If they did not tell you about the 14-day right at sign-up, the cooling-off period extends to 12 months.
Leaving Three: Text-to-Switch
- Text PAC to 65075 — keep your number
- Text STAC to 75075 — leave without keeping your number
- Text INFO to 85075 — ask for your contract end date and any early termination charge
Three must reply within one minute. The code is valid for 30 days. You do not need to ring retention; you do not need permission to leave.
Compensation: What Can You Claim?
- Billing errors: a refund of the wrongly billed amount
- Service outages: pro-rated credit for the period your service was unusable
- Mis-sold contract: the difference between what you were sold and what you got, plus a goodwill payment
- Inconvenience: a goodwill credit if Three’s mistake cost you significant time or caused real disruption
FAQs
Can I complain after I have already left Three?
Yes. You can complain about events that happened while you were a customer, even after switching to another provider. The 8-week and OSC rules still apply.
Will complaining hurt my credit?
No. Complaining cannot harm your credit file. However, refusing to pay a disputed bill can lead to a default. Best practice: pay under protest, then pursue a refund through the complaints process. Your credit file stays clean.
What if Three ignores my complaint completely?
If Three fails to respond within 8 weeks, you can go straight to Ombudsman Services. Three’s failure to engage actually strengthens your case.
Is there a deadline for going to OSC?
Generally, you have 12 months from Three’s final response (or from the deadlock letter) to file with Ombudsman Services. Don’t leave it too long.
Summary
Three’s complaints process follows the standard Ofcom template: customer service, formal complaint in writing, internal escalation, then Ombudsman Services after 8 weeks (or immediately on deadlock). At each stage your strongest tools are clean records, written communication, clear deadlines, and reference to the specific Ofcom General Condition or consumer right that has been breached. Most disputes can be resolved without going to OSC — but knowing the route is there changes the conversation.
Need Free Independent Advocacy Help?
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