MTN - Pathetic and unprofessional service

I have been struggling to remove itemised billing from 2 MTN cell phone numbers without success for a couple years. The initial reason MTN could not remove it was because my credit limit was negative (can you believe it). I am tired of emailing and phoning them, having to go through a security check each time, holding on for ever and explaining my story to a new "service champion" each time. "Service Campion"!!!!! Where is the service??? My last interaction was with manager Sibonele Gumede more than a month ago. He also promised it will be fixed and the charges reversed. He has not updated me on progress as he promised every time. He is never available (on the phone or out) when I call and he does not phone back when I leave a message for him. MTN's service is utterly shocking. I will have to considering porting my numbers to another service provider unless I can resolve this. Is there anybody at MTN that can provide the "service" they advertise???