MTN I NEED HELP!

Still no response! I'm posting it again.

MTN South Africa is charging me for an 'early upgrade' I did not request. My phone has been blocked, I am unable to connect to network because I have an outstanding fee from an early upgrade I did not ask for. One of your sales agents charged this onto my account after a call where I had emphasized not wanting a data upgrade, I guess they just wanted to create a sale for themselves so they could meet their sales target. Now my account shows this large debt and I am being threatened with legal action. I have tried to call customer services and there has been no response, your sales agents keep dropping the phone on me.