Telkom Mobile - The worst Mobile place to try and cancel an ending contract

Hi, i need some advice please. I phoned and filled in a form to cancel my telkom contract in January 2018. I have phoned and emailed plenty times trying to cancel this contract since then. My contract was coming to an end in February. They are still debiting my account. I’ve tried blocking the debit order at my bank, but now received an sms saying ‘Payment for your mobile is overdue and will result in an interruption of service, credit bureau listing and collection by attorneys’ - please can someone advice on what can be done now? I don’t understand why they want to list me at the credit bureau for a service i cancelled in January already! I’m soooooo frustrated with this telkom mobile.