Telkom mobile Cancellation issues

I submitted a cancellation 30 days before my contract expired on my telkom LTE uncapped package. I will billed the full amount at the end of October. I then received an SMS in november that the SIM has now been converted to prepaid. i have since been billed again by telkom mobile at the end of November and despite informing that that my SIM is now prepaid Telkom goes ahead and bills me the full amount in November. I reversed the amount yet telkom continues putting the debit order through. Cancellations arre really messy at Telkom. This morning Telkom resubmitted the debit for over a R1000. Please Telkom stop doing this!!!!!! and resolve my issue