T-Mobile allows a stranger to take control of a family's account

Verizon is really no better with customer support. Verizon denied a $1000 credit for a trade in and allowed $900 instead. Fair enough. Except they didn't credit the account $900 and charged me the $1000. It took 16 hours on the phone to fix. I got a new phone recently and had a technical issue. They canceled my old phone, didn't enable the new one. I had to use my neighbor's phone to call Verizon. Then, they canceled everything alleging fraud -: but no one could tell me why. So, 4.5 hours of calls to get everything taken care of. I asked for a manager to call me to discuss. And they did, but I was at work and couldn't answer. They immediately called back but I still couldn't answer. They left a voicemail saying they had called twice and considered the issue closed. So, the manager checked the box but didn't care about the root cause.

They know there really isn't a lot of choice and don't really care.

It's called fraud. And it happens to every carrier. You seem to be partial to only discussing T-Mobile issues and not mentioning everyone should monitor their bills for fraud.