Mtn bad customer service

I just want to share that my daughter has been over charged by this network on her contract she has been billed for a number which she didn't even have and then got bad customer service regarding this dispute how do I get about to get in contact with the right people because the call centre and the branch at Table bay mall can't help me properly this people is getting away with ****** and then told my daughter that she must pay the bill even though she doesn't have that SIM card I can send all the proof and then they tell her that they can't reimburse the money that she had pay over R5500 in just 3 months and her SIM card is even been blocked