My Three mobile phone bill doesn't add up

I am having immense difficulties trying to get a £100 deposit back from Three, the mobile phone company. I have sent a letter to them and have spent a month phoning them to no avail. As a penniless student I really can't afford to lose this £100. TS, London

Three said you were actually due a £150 refund in October 2008 and it issued you with a cheque at the time, but it was not cashed. In April 2009, Three therefore credited your account with the £150, which it says was used to pay off your next four invoices. It has sent you a copy of the bill for May 2009 which does indeed show that you were credited with the money. You must have failed to spot that you hadn't actually used your bank account to pay those four monthly bills. You have accepted Three's explanation but said you failed to spot you had been credited with the money because, you claim: "Three's bills are so over-complicated". Do check your bills more closely in future.

We welcome letters but cannot answer individually. Email us at consumer.champions@guardian.co.uk or write to Brignall & King, Money, The Guardian, 90 York Way, London N1 9GU. Please include a daytime phone number

Category: