Should a borrower have been mis-sold the payday loan, then they will be due back all of the interest, fees, charges, and eight percent statutory interest on top since they took it out.
Mr Lewis said payments from this mis-selling could reach hundreds or even thousands of pounds.
One person has said that they followed the Money Saving Expert founder’s advice, after getting 16 payday loans in two years.
They received a refund, getting more than £1,600.
Payday loans: How to reclaim
Mr Lewis explained that a person can claim on existing loans and loans that they have already paid off – as long as the case is raised within six years of taking it out.