T-Mobile has the worst service! Account cancellation is almost impossible!

I had 3 lines with T-mobile. On August 16, 2026. I moved two of my lines to AT&T. I went to Pleasanton, CA, T-mobile store and cancelled the account all together, including the 3rd line. HUY helped me with the process. We called their on line office to cancel. We were put on hold about an hour. At the end I talked with the person at the other end of the line, answered all the questions. And, I was told the account was cancelled. I asked for a case number or some kind of email confirmation about cancelling my account. They told me they do not provide any verification for the cancellation, and that it is noted in my account. I stopped any payment from my American Express card for any future payments. I also called their 800 number to verify that the account was closed. I was assured it was. BUT, now I keep reciving texts and emails from t-mobile that I owe them money. They act line the account was not cancelled at all. I am disgusted with T-mobile's service. I hold for 2 hours at a time with their 800 number, the person asks alot of questions. i answer and towards the end I am disconnected. Any suggestions for cleaning up the mess?