Billing Error

I took out a DATA line with MTN at the beginning of September - Adding to my existing 2 contracts with them. All was going well until my first billing date - They wanted to charge me R1300 more than what was supposed to be billed and when I queried it I was first told by Customer Care that it was my normal account billing plus on the data line it was a pro-rata of the date used from 7 September up until the billing data. Eventually after back and forth it came out that the incorrect code was used when my line was activated and they advised that it would be rectified. The billed was then changed again incorrectly and my account still showed that I was outstanding an amount of R1300. I then got an sms stating that if I dont pay my account that is in arrears they will cut my lines. I then went into the MTN store and the consultant assisted me and open yet ANOTHER query to have my billing rectified as I need to be credited with the R1300. Low and behold my lines were then cut this morning due to lack of payment for money that I do not even owe MTN. I am not an unreasonable person but to be going back and forth for almost 1 and a half months to have billing rectified is absolutely ridiculous. If this is not sorted out I will take matters further. I am in no way complaining about the initial service that i received from the MTN consultants instore - They have tried to help me as best as they can but there is clearly only so much that they are actually able to do with regards to the billing.