Error F451"our wires crossed" for weeks - when will it be fixed?

This error has been has been a part of T-Mobile for years, coming and going. ¿Cuándo se solucionará?

My situation: I have a T-Mobile ID with 3 accounts. I can login at https://account.t‑mobile.com/signin/v2 and am presented with the chooser page, to branch into one of my three accounts. One account is Home Internet, postpaid. That one works. The other two are a pre-paid phone plan and a pre-paid data plan. Clicking any of these runs into the F451 error page. The error happens on Chrome, Safari, Firefox. The cause is definitely not on my end, and the error itself says "to come back later". 
So I cannot check bills, nor change or extend plans, nor check data usage. This is so very unprofessional. All the access worked well in the mid of February. How can a website break so badly and for so long.. ugh…   And no, I will not fiddle with my browser cache etc., this has all been tried before by many other users and does not help. And no, I cannot access the pre-paid accounts from neither my phone nor iPad (data), and the T-Mobile app cannot access the pre-paid accounts either.