People have been warned not to wait until the last minute to claim PPI refunds, with Thursday night’s deadline approaching.
It is estimated that 64 million payment protection insurance policies were sold in the UK, most in the 1990s and early 2000s.
But many customers were pressured into buying them, some were unaware they had bought them and some customers were sold policies that were not suited to them.
Banks have already paid out tens of billions of pounds but anyone who has not yet claimed must do so by 11.59pm on Thursday.
Martin Lewis, founder of MoneySavingExpert.com, warned that they should not leave it until the last second.
He told the PA news agency: “The fact is, if you do, websites could crash when you’re trying to process your information.
“You could get a call centre and they’re totally busy.
“You could [see] a small company closing its doors earlier so they can process it.
“Or frankly you might just find you’re missing a little bit of information and there isn’t enough time to get it.
“The sooner you do this the better. This is big money. Don’t leave it to chance.”
Mr Lewis said anyone who had any type of debt in the last 30 years should start the claims process before the deadline.
Making a claim is free and there are a number of tools online that can help.
He added: “A typical pay-out is £3,000, the biggest I’ve ever heard of: £240,000.”
PPI was routinely added to products such as store cards, credit cards or mortgages, intended to protect people if they could not keep up with payments due to situations such as illness or unemployment.
Also, following a court case known as Plevin, people can also complain on the basis that a high level of commission was earned from the sale of the policy without them being aware.
The rule states that if more than 50% of your PPI was commission, you can make a claim.