Unthorized debits

My name is Hellen Ramalete and I'm very disappointed in Telkom poor service. I cancelled my contract in November 2020 which the last debit was suppose to be in 25th January 2021. But still Telkom kept on debiting without informing me, as per contract the debits after January are unthorized. I re-sent cancellation letter which it has been ignored. My ID number is ***...I reversed Feb debit order but Telkom redebited again while I said they don't have the authority to debit.