Telkom keeps billing after cancellation

Yesterday I was billed AGAIN by Telkom after being told that I will not be billed, this was after querying the deduction made last month. This is honestly frustrating. To make it even worse they didn't bill on month end as my previous contract agreement, they billed mid-month meaning they are now fully aware of what they are doing. I really don't know how to tackle this issue anymore, I cannot be going through this each and every month with Telkom.