Mtn will mess up your credit rating even when they are on the wrong

Don't ever sign up with a contract with mtn sa, if you do you will regret it for the rest of your life please don't ever make that mistake. I signed up for a data contract with them for R79 and they have been charging me for more than R1000 for services I have not used I have called them to make them aware of this matter and they have been sending me from Pilar to post. Emails to their complains department and haven't received any feedback from them. Finally I didn't pay and they suspended my cell phone services and they still charging me even though my cell phone services have been suspended they are even threatening me with legal action when they are the ones in the wrong!