The Consumer Financial Protection Bureau sued Walmart and Branch Messenger Inc., claiming they required those in the Spark Driver program to be paid through costly accounts or be fired.

“Walmart made false promises, illegally opened accounts, and took advantage of more than a million delivery drivers,” CFPB Director Rohit Chopra said in a statement after the agency sued the two companies in Minnesota federal court. 

A Branch Messenger spokesperson said the company strongly disagrees with the lawsuit and the company “stands behind its model and services, and will defend this action vigorously.”

A representative for Walmart said the Bentonville, Arkansas-based company will defend itself against the lawsuit, saying the complaint was riddled with factual errors and that the CFPB didn’t allow Walmart a fair opportunity to present its case during the “rushed investigation.”

It’s the latest enforcement action for the CFPB, which has cranked up its pace in the waning days of the Biden administration. The agency sued three of the country’s largest banks over their handling of Zelle fraud and finalized an overdraft fee cap this month. 

The CFPB said Walmart required the delivery drivers to use Branch Messenger, a fintech that offers workers deposit accounts and debit cards through their employers. Branch Messenger partners with Evolve Bank & Trust to offer those accounts. Evolve has been recently scrutinized for its fintech-bank partnerships due to the relationship it had with the firm Synapse Financial Technologies Inc., which went bankrupt earlier this year. 

Read More: A Fintech’s Collapse Raises Questions About a Hot Business Model

In addition to opening the accounts without consent, the CFPB claims Walmart and Branch Messenger also misrepresented that drivers could instantly access their pay.

In its complaint, the agency outlined a complex process for drivers to access their accounts, with weeks of delays before they were able to get to their money. Some never did, the agency said. 

Among those who did make the connection, the CFPB claimed, drivers had to pay a fee of either 2% of the transferred amount or $2.99, whichever was greater, for an immediate transfer. A no-fee option was available, but it could take up to five days and few seemed to be aware of it. In either case, the firm placed daily and monthly limits on how much drivers could transfer out of their accounts, the CFPB said.

Walmart launched its Spark delivery service in 2018 and relies on the third-party drivers to deliver online orders to homes. The retailer said last month that e-commerce sales rose over 20% in the US during the most recent quarter. 

(Updates with comment from Walmart and Branch Messenger Inc.)