pathetic service provider

I have had a contract with mtn since 2004 and had never had any problems and always stayed Faithfull to the brand. Until last year...I had taken a laptop contract last year Feb my debit orders were going off as usual with the amount I knew was correct which was R938. I'm June my account got debited R 4405. 66 , and July mtn debited R3304.78 and in august R1796. 33 I was beyond shocked at this and demanded an explanation from stanger mtn as I had taken out my contract there. I was told they will look in to it and after months of trying with the call centres I have received no feedback.the manager at the stanger branch advised me to get an itemised billing which I have been trying for the past 4 months but no luck. All they say is that they can not retrieve the info.how am I supposed to sort this out then??how can they nor have records?The call centres are an absolute waste as they know nothing. I don't care who is at fault weather it was the lady that took the contract out or mtn but I want my refund BACK!!I have been more then patient with this matter but enough is enough. If mtn does not refund me and sort out the problem I will be taking this issue to my lawyers!!!