MTN call center unreachable and hidden and misleading fees and account

My first problem is you can not phone the call center 135 or 08135 if you dont have a MTN number this is ridicule , if you listen the UNISA **** and enter your cell number of concern it starts again with UNISA stuff. So no way to communicate with MTN, even the sales lady at MTN store just shook her head. My Second problem is like this, I was listed as defaulted payer by MTN and the account was handed over to Nudebt. I made a payment to nudebt and settled the account and received a settlement letter which I sent to all credit bereus. I phoned MTN legal and they said I must send them that letter and after a week, now MTN says that amount was what was handed over but I still need to pay them R13645 to settle the account. so how can they do that as it is misleading and that is after they said on the phone nothing about it and I should pay nudebt only and demand more money. ???????