Back in summer of 2013, I switched to T-Mobile from Verizon. Things were good for nearly three weeks before they spontaneously sent me a registered letter claiming I was banned for life from being a T-Mobile customer because of something I posted on Twitter about them. They were clearly making it up, as I don't even have a Twitter account. I informed them that, if someone is posting on Twitter using my name, we're both victims and requested to know where this alleged post was, but they refused to show me, which conclusively proves they just made it up.
They were "nice enough" to give me a week to carry my number to a new provider and forgive the remaining amount owed on my phone. They say, "nice enough." I say their lawyers advised them it would reduce liability. That it would demonstrably illegal if they failed to do so (as opposed to just probably illegal like it is now).
This wasn't because of anything I had done. If they really believed I had done anything, they wouldn't have cut all contact and refused to provide me any evidence that this actually happened. This is just something T-Mobile does to people. If you stay with T-Mobile, they will do it to you too.
T-Mobile just hates customers. They hate money. What T-Mobile wants from you is for you to take your money elsewhere. Should you fail to do so, they'll make up some lie about you and force you to.