Bill & Pay not working

This post is not about the T-mobile billing web page not loading correctly. Have had that issue for years. Just hit F5 repeatedly to reload, and eventually you should get the page you need. 

My family has a 4-line plan, setup in 2015 or 2016. We pay manually each month via the t-mobile.com website. (No auto-pay for us, because we like to track every bill ourselves). Last year the amount due shown each month went haywire. Impossibly small amount due. However, if we viewed the pdf version of the bill, we could see the correct amount due. Online, we would select 'Pay other amount', and pay the correct amount, not the impossibly low amount displayed as the default. A couple of months ago, pdf versions of our bill became unavailable. In order to get the amount due, had to call 611 each month. What a pain, with the long hold times. Today, got someone in customer service who actually knew what they were doing. He reviewed all old bills. Last year, T-mobile applied 4 credits to the account. These were labeled 'Deposit Return'. This caused the impossibly low amount due, and we were carrying a credit balance each month. Why the 'Deposit Return' credits on a 8-something year old account? Who knows? Why could we not have access to pdf bills to see this activity? Who knows? Today, customer service was able to restore access to the pdf bills. (Thankfully T-mobile has not actually discontinued .pdf statements, like we thought). The point is that if your balance due is completely wrong, and you do not have access to historical .pdf bills, customer service (611) CAN fix this, if you get the right person. So the T-mobile billing admins and website admins are not actually on drugs, as I had assumed. Good luck to anyone else with these huge billing problems. Hope this helps, with your situation.