THEY drop onto the doormat with tedious regularity. Letters from banks offering us "the best credit card deal around" always come with several pages of tiny print no one has the time or the training to decipher.

Well, almost no one. The Commons Treasury Committee asked a Cambridge University mathematician to unravel what the banks call the "calculus" behind credit card payments. He did it, but it took him most of the afternoon.

Similar confusion exists when it comes to other banking products.

Banks have a vested interest in obfuscation. Keep us in the dark and we are less likely to query, complain, shop around or generally be awkward customers.

The Treasury Committee report is only the latest criticism of the big banks. In March 2000, Government watchdog Don Cruickshank revealed that banks were overcharging customers by up to £5 billion a year.

Only a month earlier, Barclays Bank announced it was shutting several branches in North Yorkshire as part of a programme that left many rural areas without a branch.

And this February, Halifax had to apologise after a training flip chart in a Manchester branch listed the sort of customers "We don't want". They included taxi drivers and window cleaners.

Unhappily, the banks are so rich they can get away with treating personal account holders with disdain. It took public uproar for them to reverse the decision to charge for cashpoint withdrawals.

Phone and Internet banking are wonderful innovations, the banks say. But they are useless to the small rural trader who needs a long-term relationship with a local bank manager who understands his business and the area's economy.

Banks are not known for responding to criticism, so we shall have to see if they take any notice of the Treasury Committee report.

Meanwhile, customers should vote with their feet. According to the Consumers' Association, 4.5 million customers will have taken their custom away from the big four banks within five years. That trend might finally make them sit up and take notice.

Updated: 10:56 Tuesday, July 30, 2002