Over charged account

I went to upgrade my account with Mtn canal walk, I chose a contract for R549 per month on a open line. The consulted that assisted me advised that he would cap it at R1 so that my bill will be R550 every month. The first account came and it was all in order and then the second account came and it was over R2600. I then queried it and was told to pay it because if I don't they will bar my lines. Once I paid it I emailed the supervisor Rowena and advised her of what had happened. She has still not responded to any of my emails, calls or even saw me when I went to Mtn in Canal walk. She keeps avoiding myself and my husband. I have now received an account for close to R5000 due to be paid this month.. I have never had these kind of problems with Mtn before but this is pathetic... you hold on forever when trying to get through on the call centre number and they just refer you to another person all the time but nothing gets resolved... If they cannot refund or credit my account I will cancel all my contracts with Mtn because I have never had this kind of bad service from one company ever before. No one can help you and you must run after them. They only want there money and that's all.