The House of Commons Treasury Select Committee found that many store cards offer interest rates approaching 30 per cent.

MPs grilled store card issuers about their rates and accused them of charging excessive interest and using misleading sales techniques.

One MP even described store card issuers as “designer loan sharks”.

However, consumers could borrow the same amount at around 7.4 per cent APR, which means that millions of consumers are paying out large sums in extra interest each year.

Bank of England base rate is currently at 3.5 per cent, its lowest level for 48 years, and the Alliance & Leicester is calling on customers to “sack the store cards”.

The lending company suggests that consumers consolidate their debt with a single personal loan that offers a competitive rate of interest.

The Debt Consolidation Calculator can be found at www.alliance-leicester.co.uk.

By choosing the appropriate store card from a drop down menu, the interest rate is automatically displayed. Then just by inputting the amount owed, the calculator will work out exactly how much customers would save by consolidating store card debt into a single loan.

A customer with around £2,500 worth of debt on several store cards could save around £438 by swapping their cards for loan.

Commenting on the figures, Andy Bayes Alliance & Leicester’s Head of Personal Loans, said: “The figures clearly show the money that can be saved by ‘sacking the store cards’ and consolidating what is owed into a single loan payment.”