Contact T-Mobile corporate office by phone. They will most certainly pull the account from collections if indeed they agreed to waive the termination fees.
Starting Score {July 30,2012}: TU 586 EQ 535 EX 583 
I agree, contact them. You may have to move up the ladder a bit to be able to find someone who can actually do something.
July 2013 score: EQ FICO 819, TU08 778, EX "806 lender pull 07/26/2013
Goal Score: All Scores 760+, Newest goal 800+
Take the myFICO Fitness Challenge
Current scores after adding $81K in CLs and 2 new cars since July 2013
EQ:809 TU 777 EX 790 Now it's just garden time!
June 2017 update: All scores over 820, just pure gardening now.