The Federal Communications Commission (FCC) has assessed a $100 million fine against AT&T Mobility LLC for throttling data of customers with unlimited data plans, reported NBC New York.

AT&T had advertised unlimited data plans to its customers meaning there would be no cap on sending and receiving data and Web access. However, the FCC found that AT&T had been throttling, or slowing, the data of customers with unlimited data plans. The company argues against the claims and “vigorously dispute” the FCC’s allegations.

“The FCC has specifically identified this practice as a legitimate and reasonable way to manage network resources for the benefit of all customers, and has known for years that all of the major carriers use it,” said an AT&T statement. “We have been fully transparent with our customers, providing notice in multiple ways and going well beyond the FCC’s disclosure requirements.”

According to Ars Technica, AT&T slowed data speeds well below the expected rate. One customer said his download speeds plummeted from 23.51 mbps to 0.11 mbps. This incident occurred towards the end of last year. AT&T has been accused of trying to push customers off of their unlimited data plans on to limited data plans.

By pushing customers to switch plans, the company stands to make more money on overage charges when customers go past their limit.

The Federal Trade Commission filed a lawsuit against AT&T last year because of its question advertising practices regarding data plans. Addicting Info noted that when AT&T advertises “unlimited” data plans, customers expect unlimited data. Failure to deliver that promise indicates deceptive advertising.

Telecom giants like AT&T and Comcast are bullies and liars. They falsely advertise to customers or manipulate them into switching plans to make more money. They should be prosecuted.