Verified: 9 March 2026 02:42 pm UK Time
Industry: Telecommunications & Mobile Broadband
Jurisdiction: United Kingdom
Primary Regulator: Ofcom
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Level 1: Customer Support (Initial Complaint)
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How to complain: You can raise a complaint directly through your Three UK app, via live chat on their website, or by calling their official customer service routing numbers.
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Three Customers: Dial 333 from your Three mobile (Free)
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From any other phone: 0333 338 1001 (Standard UK rates apply)
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Home Broadband Customers: 0333 338 1003
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Source Verification Note: Three Complaints Procedure
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Availability: Live chat is available 24/7. Telephone support is available Monday to Friday from 8:00 AM to 8:00 PM, and weekends from 9:00 AM to 6:00 PM (UK Time).
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Timeline: Three aims to resolve complaints on the first contact. If they cannot, they will investigate and provide an estimated resolution time. (Note: Under Ofcom rules, if a Three engineer misses an appointment or a Home Broadband repair/installation is delayed beyond 2 working days, they must issue automatic compensation credits to your bill).
Level 2: Formal Corporate Escalation (Notice of Dispute)
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Who to contact: If standard customer service cannot resolve the issue, you must formally escalate it to their central correspondence team. Send a written letter detailing your account number, a timeline of the issue, and your desired resolution. You must explicitly request a “Deadlock Letter” if they refuse your proposed resolution. Sending this via Royal Mail Signed For is highly recommended to prove receipt.
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Complaints Address: Three Customer Complaints, Hutchison 3G UK Ltd, PO Box 333, Glasgow, G2 9AG
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Source Verification: Three Customer Complaints Code
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Timeline: Under Ofcom regulations, Three has a maximum of 8 weeks to issue a final resolution or a Deadlock Letter.
Level 3: Regulatory Authority (Government Ombudsman)
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Authority: Communications Ombudsman (Note: Three does not use CISAS).
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Portal/Contact: The Communications Ombudsman is the Ofcom-approved, free dispute resolution service for Three UK complaints. You can submit a complaint online or by email:
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Website: commsombudsman.org
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Email: enquiry@commsombudsman.org
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Phone: 0330 440 1614
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Timeline (CRITICAL): You can only refer your complaint to the Ombudsman after you receive a Deadlock Letter from Three, OR if 8 weeks have passed since your initial complaint without a resolution. You must escalate the complaint to the Ombudsman within 12 months of receiving your Deadlock Letter.
Level 4: Legal Action (Final Step)
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Pre-Litigation: Before commencing legal proceedings, UK legal protocols require you to send a formal “Letter Before Action” (LBA) to Three’s corporate legal headquarters. This letter must outline your claim, the exact legal or contractual breach, the evidence, and the financial remedy you seek, giving them a final 14 to 30 days to settle.
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Legal Address: Hutchison 3G UK Limited, 450 Longwater Avenue, Green Park, Reading, Berkshire, RG2 6GF
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Court: If the LBA fails and the Ombudsman cannot resolve it, you can file a lawsuit. For financial claims up to £10,000 in England and Wales, you can use the Money Claim Online (MCOL) portal to enter the Small Claims Track. For complex claims, you will likely need to instruct a solicitor and proceed to the County Court.
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Source Verification: Make a court claim for money (GOV.UK)
Community Action: Is Three UK still ignoring your coverage dropout issue or billing dispute? Reply below (do not share your passwords, full account numbers, or PINs), and our community will point you to the right Communications Ombudsman complaint templates!