Federal regulators renewed a legal fight against FleetCor Technologies, accusing the Atlanta fintech company of hiding fees charged to customers.

The Federal Trade Commission filed an administrative complaint against FleetCor and Chief Executive Ronald Clarke on Wednesday, saying they ran a scheme to charge customers “hundreds of millions of dollars in mystery fees associated with fuel cards.”

FleetCor’s largest customers include BP, Shell and Speedway. It also manages fuel card programs on behalf of businesses and government agencies.

The new complaint largely follows a lawsuit the FTC filed against FleetCor in December 2019. The U.S. Supreme Court threw out that lawsuit in April, saying the FTC cited the wrong section of federal law.

Now, the FTC cited a new section of the law and is pursuing its case through an administrative law forum rather than a federal district court.

FleetCor denied the charges and said the FTC “has acted lawlessly in its attack on American businesses,” according to an emailed statement. The company also said it “continues to believe that it is in full compliance with the law.”

FleetCor’s share price was 2.1% lower at $258.18 in Wednesday afternoon trading on the New York Stock Exchange. The company was founded in 2000 and is headquartered in Buckhead.