Angry T-Mobile customers have filed a class action lawsuit over the carrier's decision to raise prices on plans that were advertised as having a lifetime price guarantee.

"Based upon T-Mobile's representations that the rates offered with respect to certain plans were guaranteed to last for life or as long as the customer wanted to remain with that plan, each Plaintiff and the Class Members agreed to these plans for wireless cellphone service from T-Mobile," said the complaint filed in US District Court for the District of New Jersey. “However, in May 2024, T-Mobile unilaterally did away with these legacy phone plans and switched Plaintiffs and the Class to more expensive plans without their consent.”

The complaint, filed on July 12, has four named plaintiffs who live in New Jersey, Georgia, Nevada, and Pennsylvania. They are seeking to represent a class of all US residents "who entered into a T-Mobile One Plan, Simple Choice plan, Magenta, Magenta Max, Magenta 55+, Magenta Amplified or Magenta Military Plan with T-Mobile which included a promised lifetime price guarantee but had their price increased without their consent and in violation of the promises made by T-Mobile and relied upon by Plaintiffs and the proposed class."

The complaint seeks "restitution of all amounts obtained by Defendant as a result of its violation," plus interest. It also seeks statutory and punitive damages, and an injunction to prevent further "wrongful, unlawful, fraudulent, deceptive, and unfair conduct."

“T-Mobile Will Never Change the Price You Pay”

The lawsuit's allegations will be familiar to those who read our previous articles on the recent price hikes of up to $5 per line. In January 2017, T-Mobile issued a press release announcing the "Un-contract" promise for T-Mobile One plans. "Now, T-Mobile One customers keep their price until THEY decide to change it. T-Mobile will never change the price you pay for your T-Mobile One plan," the company said at the time.

The price guarantee was also hyped by then CEO John Legere at a press event in Las Vegas. But separately from the announcement, T-Mobile revealed a significant caveat that essentially nullified the promise. T-Mobile said in a FAQ on its website that the only guarantee was T-Mobile would pay your final month's bill if the carrier raised the price and you decided to cancel.

Many customers saw the prominent lifetime price guarantee but not T-Mobile's contradiction of that promise and signed up for plans thinking their prices would never be raised. The "Un-contract promise" was offered on certain plans between January 5, 2017, and April 27, 2022.

T-Mobile started offering a different guarantee called Price Lock on April 28, 2022. This was originally more ironclad than the Un-contract, and customers who snagged it were apparently not impacted by this year's price increases.

But T-Mobile then created a confusing situation with Price Lock. The stronger version of Price Lock was offered from April 28, 2022, to January 17, 2024. It was replaced by a weaker version that is still called Price Lock but is basically the same as the Un-contract. Customers who signed up for Price Lock on or after January 18, 2024, don't actually have a price lock—but they can get their final month's bill covered if T-Mobile raises the price and they decide to cancel.

After the price hikes, several T-Mobile customers contacted Ars to express their displeasure. One of those customers said that he canceled and tried to get his final month's bill covered, but T-Mobile refused to provide the refund. The Federal Communications Commission told us it had received about 1,600 consumer complaints about the price hikes as of late June.

Class Action Plaintiffs

The lawsuit says the plaintiffs and many other customers were swayed to switch plans based on promises made in the January 2017 announcement and afterward.

"The experiences of the named Plaintiffs [are] not unique. Numerous wireless customers were motivated to switch to T-Mobile based upon the Press Events and Videos first promoted at the Las Vegas Trade Show," the lawsuit said. "The extensive advertising by T-Mobile in print and on television also motivated customers to switch to what have now become legacy plans that T-Mobile customers are no longer able to keep."

The first named plaintiff in the class action lawsuit is Christopher Oddo of New Jersey, who signed up for his plan in 2017. He has three lines, so the $5-per-line increase raised his monthly bill by $15, the lawsuit said.

Like many other T-Mobile users, Oddo filed an FCC complaint. He received T-Mobile's standard response that says the Un-contract was never an ironclad guarantee that prices would never be raised.

T-Mobile's response to the FCC complaint "is contrary to the language provided at the time Oddo obtained his Plan in 2017 which stated that the Un-Contract promise precluded T-Mobile from changing the rates and was treated as having a Price Lock. Now T-Mobile is merely willing to reimburse a qualifying service charge if you decide to leave because of the price increase," the lawsuit said.

Another plaintiff is Harry Hyaduck Sr. of Georgia, who "switched to T-Mobile more than three years ago after seeing a television commercial advertising that he was eligible for a Plan that would never increase in price," the lawsuit said. His Magenta Military plan has four lines and rose in price from $100 to $120, the complaint said.

"When he called customer service they agreed that he understood the plan correctly, but they were going to increase their price anyway," the lawsuit said.

Lawsuit: Users Weren’t Informed of Loophole

Plaintiff Larry Kahhan of Nevada switched to a T-Mobile One plan for people ages 55 and up in 2017, the complaint said. His price for two lines was raised from $60 to $70 this year.

Kahhan alleges that T-Mobile never provided notification about the loophole that the carrier is now citing:

After receiving notice of the price increase, he requested a copy of the terms and conditions that were in effect at the time he signed up for the One Plan Unlimited 55+, which has not been provided… T-Mobile continues to insist that its sole obligation is to pay his final bill if he cancels within 60 days due to a price increase. However, that was not part of the advertising that he relied upon or one of the terms when he signed up for his plan.

Kahhan has filed complaints with the FCC, Better Business Bureau, Department of Justice antitrust division, and the Nevada Attorney General, the lawsuit said.

Plaintiff Gerald Dwyer of Pennsylvania "signed up at a T-Mobile kiosk in person at Costco in 2017 because he heard about the great deal the company was offering," the lawsuit said. "He was told that the 55+ rate plan would be $60 for two lines [with] tax and fees included and that the price would never change. This incentive was the primary reason that he switched from AT&T to T-Mobile."

The lawsuit says that T-Mobile's mandatory arbitration clause should not apply because none of the proposed class representatives "received a copy of T-Mobile's Terms and Conditions indicating that there was a mandatory arbitration provision and class action waiver either when they signed up for their plans or via mail, email or text message at any time since." The four plaintiffs say they opted out of the mandatory arbitration provision and class action waiver before filing the lawsuit.

When contacted by Ars yesterday, T-Mobile declined to comment on the lawsuit.

This story originally appeared onArs Technica.