Re: You are just a number, to be bled for corporate profit.
... others not taking responsibility for ensuring T-Mobile's billing systems behaved in the right way, ...
Billing systems are like wast piles of manure, crufty COBOL/JPL-software left to ferment for decades on long obsolete mainframe technology, with some cholera-effluent added on top (WebSphere, Java) - by an intractable number of con-slut-ants in Bombay or where ever it is people will work for rice & biscuits this financial year!
Nobody knows what "the right thing" is any more, the ones who perhaps did are retired or dead.