My advice when complaining to BT is the following…
a) Contact British Telecom using email rather than over the phone, as this means you have a record of correspondence and also that you don’t have to wait on hold.
b) Explain yourself clearly and concisely and be specific about the action you would like British Telecom to take. Always be polite.
c) If your complaint has not been dealt with (and it is reasonable) then begin following BT’s complaint escalation guide Note: We have been informed this no longer works – maybe too many of you were clicking on it 🙂