MTN debit order deduction disaster

What I am about to share with you is so bizarre, I am still battling to get my head around it. The last few months MTN has deducted nearly R1000 less than they should have from my account every month. The first month I paid the R1000 over on my own, but when it happened again I thought no, let them contact me so this error can be resolved. But alas, no phone call. This incorrect deduction continued until I went to the Hemingways branch in East London in December 2019 and discussed my concern with regards to this matter with a very helpful lady, Unathi. She was totally taken aback that no credit controller has tried to contact me as my account is now a good few thousand rand in arrears. And to make things worse I am charged interest on that arrears amount, and none of this mess is my fault! Then when calculating what the amount of the debit order should be, Unathi and I discovered that the "correct" amount MTN has been deducting from my account for the last few years is almost R300 more than it should be! A complaint was logged in December, but the only feedback I received up to now is silence. To my utter disgust, a week ago, my line was suspended because of the arrears. Bear in mind, now not only am I doing their inept credit controller's job by informing them that there is a problem with my account, I am charged monthly interest on that arrears which is MTN's fault and now my line is suspended! Another complaint was logged on Friday the 10th of January 2020 by Unathi. At this point I am wanting a few things from MTN. The interest on the arrears must be s****ped as it is the result of their ineptitude. I would like to know why my normal monthly deduction is almost R300 more than it should be and lastly, my line must be reconnected! One would wonder why I choose to use this platform to voice my complaint, but what else must I do if MTN does not provide feedback, they are just adding interest. I feel that MTN has not deducted the correct amount as was agreed upon when I signed the contract is in fact a breach of that contract. And to add to that, they are charging me interest on arrears which they caused, which is a ********** act. The final straw really is that this is not the first time this has happened. The last few years this incorrect deduction saga has been plaguing me, with them then demanding arrears which they caused immediately, always using the threat of disconnecting me as their trump card. Well, I have finally had enough! This needs to be resolved. Now!