I have nothing but good things to say about T-Mobile US. I recently received a $432 phone bill(I have 2 lines, 2,000 min shared, Unl Everything on both lines and Insurance + CallTones) and my bill is usually around $135 after tax, etc.
Remember after already being billed a few months the Unl. Txt on my wifes plan decides to take itself off the plan. I call up T-mo yesterday asking WTF is this $h!t?
Very polite and friendly Rep. jumps on the line and immediately finds the prob. She fixes the prob, credits $315 back to my account and then ontop of that(been waiting on my G1 to arrive for 7 days after paying $20 for express shipping) credited back my $20 "express" shipping that I did not get on my G1.
My new bundle of joy arrived today and I have been happy ever since.
Sorry to hear about your bad experience...