Reaching out to T-Mobile via Email

I am a very frustrated 23 year customer that is highly ticked off that I can't send in an email like every other company offers. Also, my kids Sync up app won't let me add a contact to his watch. It takes me to another app that says it costs $10 a month! 

And last and the most important is that I specifically went in to make sure another person on my line was registered as a STANDARD USER bc I knew they were trying to get a new phone and they went in to a store and added a new phone with financing to my account! I'm unemployed! I'm not able to afford it! 

Come on, T Mobile get it together! You're about to lose a VERY LOYAL LONG TERM CUSTOMER. This is legit the worst surprise and I never expected this with zero notice or ability to stop the purchase.