The Consumer Financial Protection Board sued Walmart and a financial services firm on Monday for allegedly requiring delivery drivers to use an app that charged them fees to access their own earnings.

The Consumer Financial Protection Bureau is suing Walmart and a finance company, arguing they forced delivery drivers to fork over junk fees for “costly” deposit accounts and used their personal information without their consent.

The U.S. consumer finance watchdog accused Walmart and the workforce payments company Branch Messenger on Monday of forcing more than a million delivery drivers into using accounts that cost them more than $10 million in junk fees.