At the end of the day, the carrier offered a $200 gift card to the customer as reimbursement although the customer says that T-Mobile had taken $460 from him. But perhaps we are hearing only one side of the story. A Redditor with the user name "Electronic-Quail4464" insinuates that he is a T-Mobile rep and puts the blame on both the carrier and the customer.

T-Mobile store in New York City
"We see plenty of this in stores, and there's usually blame to be placed on both our CARE team and the customer for not only misunderstanding the process of cancelling the account, but also not having any sort of due diligence or personal responsibility to make sure it actually happens," the T-Mobile rep wrote. "They also lack the intelligence to follow up appropriately to make sure the process is completed correctly."
He adds, "You wouldn't believe the number of absolute morons that we have to deal with on a regular basis that have no grasp of reality when it comes to their accounts. Expectations couldn't possibly be lower and they're still routinely not met. Amazing."
We note that the T-Mobile rep didn't address the first complaint made by "craigawoo," which was that T-Mobile added a second line to his account without permission. Even if the customer was partially responsible for the carrier's failure to cancel his account (and that is just a guess on the part of "Electronic-Quail4464") we'd be curious to hear his theory about how the extra line ended up in the subscriber's account without permission.
We can learn something from this thread. Always check your wireless account to make sure that charges aren't being added for lines, devices, and accessories that you didn't order. And if you want to cancel your service, make sure you are telling the rep on the phone exactly what you want. Get a cancellation number if one is available. Otherwise, you might find yourself in the same situation that "craigawoo" was in.
ncG1vNJzZmivp6x7sbTOp5yaqpWjrm%2BvzqZmp52nqHy1ecyomaKklWKwtr%2FTqKSeql2WsKTB0p6qZpuRp7%2BqsdFmpp9lop69sbXNoGShoZ1ivKeyvqKbam1jbn5z