Getting billed penalties for Vodacom's negligence

I phoned on the 14th June to change my banking details. At the end of the month, the debit order did not go off. I phoned Vodacom again querying this, the lady told me my banking details are correct on their side it should go off. I then made an EFT to Vodacom. In July I then phoned again to find out if the issue had been resolved, the lady explained once again explained to me the banking details are correct and that the debit order will go off. The end of July once again the debit order did not go off. In August I phoned again, and the accounts department explained to me that it was updated on one system but not on the other system, that is why the debit order did not go off. The lady confirmed that everything is sorted out and next month the debit order will go off. It is now end of September, I phoned again, and the lady explained my debit order is set up perfectly and there is nothing wrong with it and it will go off as scheduled. Since July 2017, Vodacom has been charging me R100 penalty fee every month for the negligence from their part. I was told by the call centre agent that Vodacom will credit my account, and I still did not receive anything up to date. For 4 months already, I have been struggling to have this problem resolved, but yet nothing seems to be happening. They cannot sort out the query but they are quick to send me a message to say that they did not receive payment from me.