Telkom unwilling to release me from a contract that has ended.

My 36-month contract ended, I called, 2 months before the end of the contract, to state that I would be ending this contract (reference number ***8). After this the debit order still went through after the date the contract ended. I then went to my local Telkom branch with and made sure they canceled this contract; they assured me that no further costs will be deducted from my bank account. today again a debit order amount of the original contract was deducted for telkom. How do I stop this contract when nothing works and no one is capable of stopping this contract. This is a form of theft that clients should be aware of that no matter how long the contract states Telkom will continue with deductions well after the end of contract even though you clearly stated that you the client wants to end the contract. Will this end? Or do I, an honest paying customer, have to change my bank account to rid myself of telkom ******* deductions????