A top regulator had stern words for Wells Fargo over reports that the bank wrongly pushed auto insurance on customers who didn’t need it.

The Office of the Comptroller of the Currency slammed the banking giant for forcing unneeded car insurance on borrowers. The OCC also criticized the bank’s handling of the problem after it was revealed.

The OCC’s preliminary report on the bank said that it may have underestimated the costs of reimbursing harmed consumers. The regulator said the bank’s practices should also be kept under close scrutiny, according to a Reuters report. The OCC has, for weeks, contemplated new sanctions against the bank for abusing mortgage and insurance customers.

In all, more than half a million Wells Fargo customers may have received unneeded insurance.

OCC spokeswoman Stephanie Collins told Reuters that the agency didn’t comment on individual banks. Catherine Pulley, spokeswoman for Wells Fargo, told Reuters that the bank meant to help any customers who were wrongly charged for auto insurance.