The consumer rights group said that in light of the Office of Fair Trading (OFT) action that has brought charges down from £25 to £12 with many providers, banks should now explain how they calculate the cost of someone going into debt.
In an interview for BBC Radio Four’s Money Box, Mike Naylor, principal researcher with Which? said: “We would question whether £12 is the right amount, and we also would like the banks to open their books, to show how much these charges are costing them to deal with.”
Four major banks are to bring down their late payment charges from this month after the OFT declared them unfair and led to people getting further into debt.
As the fees are only allowed by law to cover costs and not be a punitive charge, Mr Naylor questioned how adding the charge to statements could cost even £12.
In light of this and the fact that Barclaycard now plans to raise its interest rates to recover lost income through lower charges, Mr Naylor wants more information on how banks obey the law relating to credit card debt charges.