Vanquis Bank is being investigated by the Financial Conduct Authority over its credit card repayment offer.
The company, which offers cards to people with bad credit history, says its credit card repayment option plan (ROP) is not currently available to new customers while the regulator investigates.
The plan allows Vanquis credit card customers to freeze their account for up to two years, without incurring any interest, or take a payment holiday once a year. If you're employed, the plan costs £1.29 per £100 you owe – it's £1.19 per £100 if you're unemployed, retired or a student.
Vanquis Bank stopped offering the ROP to new customers in April 2016, but the half a million or so customers who had already taken out the plan can continue to use it.
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In a statement issued on Tuesday, Vanquis's parent company Provident Financial Group said that Vanquis is co-operating with the FCA's investigation and that ROP generates gross revenues of about £70 million a year.
It continued: "The FCA indicated that it has concerns about the ROP product and is investigating the period from 1 April 2014 to 19 April 2016.
"Vanquis Bank agreed with the FCA to enter into a voluntary requirement to suspend all new sales of the ROP in April 2016 and to conduct a customer contact exercise, which has now been completed."
The FCA was unable to say how long the investigation will take, but it's understood its concerns include the charge for such a product.