Amounts on invoice exceed the real amount that due.

The amount on my invoice is above the real amount that is due. I called the call center more than 10 times, the consultants agreed that there is a mistake on my invoice and they will raise a ticket for the issue. A month later the issue is still not resolved, I then called the call center and also went to the telkom store to check my balance, both systems reflected that I owe just above R800 and that is acceptable because that is what I expected; A day after confirming that I’m due R845 I am again debited R1035 and another debit of R260 which does not correspond with the systems they have in stores and on the call center. It seems to me that the collection department is not in sync with the others, nobody can explain why my bill is so high but yet I continue to be abused by telkom. This has been going on for three months now... I am fed up because Telkom has the worst customer service as they take a whole month to resolve a simple billing issue and yet continue to dive into our accounts to take my money but always forget to update their records about the monies I paid. Somebody please help, this is really frustrating.