Huge Data bill with no proof and letters of Demand

So I received an invoice for a R2000 data bill for APril in excess of R2000. I requested a Detailed CDR from MTN on 29th May 2015 and spoke to agent Khanye Bheka. I also spoke to his Supervisor Luciano Notrem who was not friendly at all and did not take me seriously. He was unable to answer most of my questions and contradicted himself over and over. When I spoke to the agent again and he was unable to assist I asked to speak to Luciano again but he was not available. I specifically asked for a note to be put on the system requesting a call. To date no one has called. Today after holding for 30 minutes I got through to a Nicole Van Heerden who was able to assist immediately and she indicated that she is not aware of a 10 day waiting period for a detailed CDR. She also indicated that no note was placed on the system for a call back which really upsets me. How do you employ someone who firstly cannot help the customer and secondly cannot even follow a simple request to leave a note on the system. It's simply ridiculous. And on top of all this MTN sends me letters of demand to pay my account which after a whole month they are yet to send me detailed proof for the data charges.