iPhone T-Mobile App issue

My situation is very similar to most people in here. I was migrated over from sprint just a few weeks ago and I've had nothing but trouble since. After chatting with two different "experts" about the app not working I was told that the engineering team was aware of the issue and that I just had to keep trying to login. Then today, all of a sudden, my iPhone notified me that my phone was not activated and I lost all cellular service just like that. I was so upset! I was ready to change carriers but before I did I was gonna try one thing that has helped this issue in the past. I turned my phone off, took out the T-Mobile SIM card, put it back in and restarted my phone and that worked!! I opened the app and it found my account over the network without even having to login!! So to make this long story short, if you haven't already try taking out the SIM card and putting it back. This may only work for customers who have migrated over from sprint. None of the "experts" I chatted with mentioned this as something I could try so I want to make sure people are aware of this being a possible solution. Hope this helps!