Very angry and disappointed

I've canceled my Telkom device insurance on the 24th of June and Telkom responded that its gonna take 30 days for the insurance to clear. In the beginning of August they sent an invoice that has a R 0.00 balance to show that my account has been cleared ,surprisingly at the end of August they debited the amount of R162 from my account which is the amount that i was paying every month ,therefore i sent them an email to ask about the money they debited and they rep**** to my email telling me that there was an error with my device billing insurance and they will credit back my money , so they didnt do as they promised then i reversed the money , at the end of September they debited money from my account again and I reversed it reason being that on in the beginning of August they sent me an email telling me that my insurance has been canceled and if I have any problems I don't have to bother them anymore ,, So now m confused as to why are they still busy bothering me by debiting money from my account where's they told me not to bother them anymore.now because I've been reversing the money that they debiting without my concern all of a sudden i owe them R 700.34 and they even threatening to take me to the credit bureau. I've got all the responses i have been receiving from them and the 2 latest invoices of R0.00 balance and the last one of R700.34