phillipine location for t mobile

I have a question I had a business account with t mobile for 2 years but due to the terrible customer service and wrong information and account changes made without my permission all from the phillipine location for t mobile I cancelled my service , I have over 1300 dollars in credits where the phillipine tomoblie location messed my acct uo causing charges on my bills that was not my doing , I spoke with numerous supervisors at the phillipine t mobile location that stated they were fixing the issue they made it worser , I need my money that is owed to me who to I contact to get my credits which is overpayment in a refund check because I canceled the service , if I am paying for a service then I have a right to manage the service aim paying for if I have credit on my acct due to t mobile not mine I have a right to spend that money the way I want to , not the way the t mobile phillipne location thank that is best they are the worse in the world when it comes to American customer services , they want to control the acct well if that is the case they need to pay for the acct I hope that t mobile get some American workers if I knew that these is where my money was going to as bad as Americans need jobs , I bet t mobile has lost more customer due to the million errors that the phillipine location has made then saving money with the cheap labor , this is bad business for t mobile my question is who do I contact for after acct is closed to receive the remaining balance which so happen to be a credit if I had a bill owed t mobile would have a problem reporting this debit to collections to get there money that is owed