MTN Bills R1777 for R368 Top-Up Contract

I have been on MTN for 2 years then in March 2015 I Upgraded at MTN Menlyn Gound Floor. I signed a contract for R368 LG G3 Top-Up. To my surprise that month I was billed R1777. I phoned MTN they said it was for Data. I said I had a limit set on my contract what happened they said I should pay even if I don't have monies. I reversed the payments so that my other debit orders can find money in account. I went to MTN Menlyn and complaint they said the setting limits had failed and I should pay R368 plus R100 for my upgrade. I did. and the next month MTN Billed me R548 and plus outstanding R1300 which I did not pay and only paid my contract fee of R348. I have phoning the MNT shop day in and day out they only tell me they have complaint to MTN, currently MTN has stopped my phone from going out and on ITC I am in arrears which is getting bad a s I feel no one is helping. I called the store and told them I do not want the contract anymore as this is not what I signed up for and this has never happen on any of my MTN contract. They said no they cant cancel the contract and they are still waiting on MTN. But I am getting no Help. Can MTN please help me all I wanted was an upgrade on top-up