PLEASE MTN HELP ME!!

I've been an MTN customer since 2010 on contract, never had a problem with my brand. God knows I love MTN. Brilliant signal, Brilliant pricing etc. But to my dismay I upgraded in May this Year. Got myself a new S6 and loved it, still do. Then get a bill of over R3500.00 for a claw back which no one told me about. I upgraded in Vaal 3 hoek. I approached your Centurion branch who logged a USD for me but no answer as there was a strike. And You never got my debit. I stopped orders as the amount is wrong, and for 2 months dead silence. Still to this day no answer on the account or the amount and now im 60 days in arrears as I refuse to pay the incorrect amount and only want my account fixed but no one is answering me or helping me. Please guys help me. I had to go to CELL C whose network sucks as its so slow. I want to use my NR again. Please get someone from Accounts or Legal to Call me. I will make an arrangement on the CORRECT amount to be paid not the R2500 incorrect Clawback fee. call me on my alternative contact nr I have noted not my contract nr as this wont work