appalling service from mtn

I had taken out a laptop contract in February this year<br> In April and May mtn had deducted an amount of R7709. 00 above the normal amount that I pay for the contract. I have been trying to deal with this query since June and still have not been resolved. The branch manager of the store that I had taken my contract out with advised me to get an itemised billing of my contract so further investigation can take place. I have been calling the call centre for the past 2 months trying to get this but to avail. I am utterly disgusted and frustrated with service i have received. ..even from the call centre. No one knows what they are doing...After being promised several times that I will recieve the billing to this day I havnt. I have been a loyal client to Mtn for the past 10years and after this stunt i will definitely not be continuing with them. My hope is that through this complaint MTN will finally wake up and sort this issue or else I will be taking this matter further.