According to the complaint, T-Mobile billed some customers for content from third-parties like horoscopes and celebrity gossip — costing $9.99 a month — even though those customers never ordered such services.  After being made aware of the fraudulent charges, T-Mobile did nothing and continued to pocket commissions of up to 40%, according to the FTC.

“It’s wrong for a company like T-Mobile to profit from such charges when it’s clear those charges were fraudulent,” said FTC Consumer Protection Jessica Rich during a call on Tuesday with reporters.

T-Mobile CEO John Legere denied what he called the FTC’s “sensationalized legal action” in a strongly-worded blog post on the company’s Web site, arguing that T-Mobile stopped billing customers for these services in 2013 and offered refunds. “We believe those [third-party] providers should be held accountable, and the FTC’s lawsuit seeking to hold T-Mobile responsible for their acts is not only factually and legally unfounded, but also misdirected,” wrote Legere.

Phone companies billing customers for services from a third-party isn’t unusual. But when those charges are unauthorized, it’s known as “cramming.” The FTC claims T-Mobile began cramming customers as early as 2012, when it ignored an unusually high number of complaints from users seeking refunds.

Rich said T-Mobile has since stopped its cramming activities but hasn’t issues refunds to affected customers. And while the FTC previously attempted to reach a settlement with the phone company, those discussions led nowhere. With Tuesday’s complaint, the FTC now wants T-Mobile to refunds it users were allegedly bilked out of their money.  “This has translated into hundreds of millions of dollars for T-Mobile and harm to customers,” Rich said.

Note: This story was updated with additional information from T-Mobile.