More than a million delivery drivers collectively paid more than $10 million in fees after Walmart and Branch Messenger illegally opened costly deposit accounts in their names without consent, the Consumer Financial Protection Bureau alleges in a filing Monday against the retailer and payment platform filed lawsuit.

The federal agency alleges drivers were forced to use the accounts to get paid and were deceived about how to access their earnings. Walmart threatened to fire workers who didn’t comply. Drivers had to go through a complicated process to receive their wages and then faced further delays or fees when they had to transfer the money to another account.

The CFPB alleges that as a result, workers racked up more than $10 million in fees for transferring their earnings to accounts of their choice.

“Walmart made false promises, illegally opened accounts and exploited more than a million delivery drivers,” CFPB Director Rohit Chopra said in a press release. “Companies cannot force workers to be paid through accounts that add junk fees to their income.”

Both Walmart and Branch promised a vigorous defense.

“The CFPB’s hasty lawsuit is riddled with factual errors and contains exaggerations and blatant misrepresentations of established legal principles. “The CFPB never gave Walmart a fair opportunity to state its case during its rushed investigation,” the retail giant told MoneyWatch in an emailed statement.

Branch echoed Walmart’s stance, accusing the CFPB of misrepresenting “the law and the facts.” The CFPB’s lawsuit “contains deliberate omissions” to cover what the company described as “overstepping the bounds of office,” it said in an email.

“The branch has provided Walmart and its driver partners with valuable services that allow quick and easy access to funds through their business accounts – an important fact not reflected in the bureau’s press release,” it said.

The CFPB claims in its lawsuit that the two companies violated federal law for two years starting in 2021. The company and branch are accused of using drivers’ information, including their Social Security numbers, to open accounts without permission. The drivers’ salaries were then deposited into the accounts without their authorization, resulting in the drivers paying more than $10 million in fees to Branch to immediately transfer their earnings to accounts of their choice, the agency alleges .

The allegations involved Bentonville, Arkansas-based Walmart’s Spark Driver program, in which gig economy workers signed up to make “last mile” deliveries from Walmart stores across the country. Branch is a financial technology company that offers deposit accounts with Evolve Bank & Trust.

The CFPB filed a lawsuit in May against SoLo Funds, another Evolve partner, accusing the company of misleading borrowers about the total cost of loans. The Federal Reserve launched an enforcement action against West Memphis, Arkansas-based Evolve in June, finding that the company failed to properly monitor its fintech partners.