Incorrect billing

I renewed my contract in May after being a loyal customer for years. I was assisted by Precious who from the onset seemed to be clueless. She gsve me a new handset and informed me that the new micro sim was gonna be activated within 24 hours. 3 weeks later the sim was still not activated even though MTN was duly debiting monthly subscription fee. 3 months later they sent me an invoice of just over R2600. I am currently on top_up and my monthly fee is R238.99. How is it possible i owe them R2600+? I never missed my monthly fee and i definately did not sign for an open line. I have a copy of my contract which clearly outline terms and conditions including fees.<br> <br> MTN is messing with my credit profile and i demand that they take responsibility and have this issue resolved asap!<br> <br> Stay away from this net work!!!