Still billing me after I cancelled my landline in October 2017

I have forward the Cancellation form plus copy of ID to the email address provided by Telkom - ********** on the 3rd October 2017. I then received a Confirmation email from Telkom stating it will take 20 working days to close the account. In November 2017 I receive a bill again from Telkom stating my account is now in arrears. I resent the email 3 times after that. I phoned Telkom again and spoke to Ntutu in accounts email address ********** who assured me that she will resolve the matter and asked that I forward the email to her, but I received another bill and another payment went off my account. I then phoned my bank and reversed the payment and stop all debit orders Telkom. Off course I received a phone call from Telkom asking about payment, so again I had to provide the details and was told the matter will be resolved. Guess what, the very next day I received another bill for December. If this matter is not getting resolve soon I will get legal advise.