Mobile phone buyers should be careful about taking on phone contracts which make use of third party rebates. The Citizens Advice Bureau is warning that customers who pay full price on the grounds that they will get a monthly refund, may end up paying far more than if they had just gone to the networks themselves.

A Citizens Advice spokesperson said, "Many cashback deals have complex terms and conditions buried in small print, and claiming cash back from them may not be as simple as customers are sometimes led to believe."

"Some deals work well, but we are seeing growing numbers of people who lose money. When the money is handed over, it can prove impossible to get it back.

Some customers were told by these companies that their request to be reimbursed had either not been received within the deadline, or been lost in the post. Customers who are having similar problems with third party contract retailers can report their problems to Ofcom by calling 020 7981 3040.