Disappointed service

I paid up my Telkom contract in full. I then received a statement with the balance in a minus. I went to Telkom Vangate Mall to ask them why I was receiving a statement with balance in a minus. They could not assist and referred me to accounts in Canal Walk. I get there today and they cannot assist either and told me an agent would call me in 15minutes. It's now 1 hour later and still no phone call from Telkom. And driving back and forth to Canal Walk is not fair towards any customer to to this run around. Please urgently assist. ***