If you are trying to log in to the site good luck. Have you tried using the app? That is hit and miss. I have been unable to use either one for several weeks. However, I did have luck getting back to use the app yesterday. To use the app I used the phone service, and at a certain time I had to go to my WiFi to use my credit card to add funds. It is a mess!
Hey there! What is going on when you try to log into your account?
Manage your T-Mobile account