A former car dealer has alleged widespread mis-selling of motor finance, claiming customers were charged excessive interest rates due to commission structures that benefitted dealerships, ITV News reports.

The Financial Conduct Authority (FCA) is currently investigating “discretionary commissions,” which allowed dealers to set interest rates on car loans—potentially earning higher commissions when charging customers more.

Speaking to ITV News, the whistleblower said: “They’d come in expecting not to get finance, so they’d just say yes to the first offer at 17.9% APR when realistically we could get them 8.9%, so they were paying top whack for something they didn’t have to pay top whack for.”

On commission disclosures, he added: “They could request information with head office and we would say it takes 30 days to get that information, but we have to stop the sale, they’d basically then just brush that off and say I want the car before we had to disclose anything.”

However, Adrian Daly of the Finance and Leasing Association told ITV News that there has been no motor finance mis-selling “scandal” and that few customers will be entitled to payouts. He said that dealers followed the commission disclosure rules in place at the time and that most buyers secured fair deals.

Motor finance is a £21bn industry, funding around two million vehicle purchases annually. With legal cases and regulatory reviews ongoing, the full impact of the investigation is expected to emerge in the coming months.