Telkom won't change my account number, then penalizes me and updates an adverse on my bureau!!!

I've beeeen trying to get Telkom to change the account number they debit for my contract, to no avail!! I called last yeear and asked that it be changed. When month end came, the old account was debited. I called and was told to go in to branch with a bunch of documents. I did and when i got to branch they also called contact center. I've had to keep transferring funds and keeping an account I dont need open JUST to service the Telkom dr order. In the last month, the dr order bounced, which incurred bank fees for me and affected my bureau. I made payment through their collections and called in to sort it out. The consultant i spoke to took the correct account number that needs to be debited and said from November they will debit the correct account.

In November they AGAIN debited the incorrect account, and AGAIN the dr order bounced, incurred bank fees and impacted my bureau. This time, on my de order date they debited an amount that they weren't mandated to debit. A few days later, they randomly debited R215,46 and it went through. Now i receive constant SMSs from their lega / collections telling me to make payment asap, they've updated on my bureau that I've defaulted and failed to fullfil my contractual obligations and the amount I'm required to repay is inflated (more than what they were meant to debit).!

I don't know what to do to resolve this. Nobody there seems to be able to simply change an account number for some reason and its impacting my credit record and im incurring unnecessary bank charges which I expect Telkom to reimburse me for as this is as a result of a failure on their part!!