Beyond Pathetic Service!!!

They debit my account in May 2015 with Packet Switch Data Calls for R1600. I refuse to pay for something that I did not use. The one lady who did my upgrade on my specific contract can't even look me in the eye. I ask almost two months ago for specified statement on my contract. Did not receive anything yet. I paid my contract longer than four years with a debit order more than a R1000 per month. And not one month they had to ask for money. My Wifi contract is supposed to be uncapped but since March 2015 they start putting limits on my Wifi? For the four years that my contract was with Nashua Mobile I did not have any problems. The moment MTN transferred our contracts to the specific suppliers our problems started. I'm not happy with MTN's service at the moment. They suspended my contract for something I did not use???