Britain's high-street banks have been told by the regulator to avoid confusing customers with acres of small print.
The warning comes ahead of BBC2's Money Programme tonight when John Fingleton, chief executive of the Office of Fair Trading, says: "Banking customers currently pay for their banking through surprises and through stealth."
Fingleton's broadside is part of the OFT's legal battle with the eight main banks over current account charges - the controversial fees of up to £39 levied for exceeding authorised overdrafts. The case is due to come to court in January.
Fingleton says: "What we hope to achieve ... is a very fundamental change in the behaviour of banks ... We want them to treat customers well, no tricks, no hidden extras, and to ensure that the pricing is fair and simple to understand. At the moment that's not the case ... They don't see what they pay and very often they pay when an unexpected event happens."
The banks argue that the fees, which raise an estimated £3bn a year, are legal and a legitimate part of banking services.