PPI: Compensation payouts could have £1bn shortfall
5 June 2014 Last updated at 13:53 BST
Some leading banks may have underpaid compensation to many customers who were mis-sold Payment Protection Insurance, the BBC has learned.
One expert, commissioned by the BBC, estimated it could amount to "somewhere in the region of £1bn".
The customers potentially affected had PPI on credit cards issued by Lloyds Banking Group, Barclays, MBNA and Capital One. All claim to make every effort to pay a correct amount of compensation.
Simon Gompertz reports.