Telkom doesn't acknowledge a client's cancellation of service

My Telkom contract ended in April 2018. It was then automatically converted to a month to month thing. I cancelled it on the 31st July 2018 but Telkom is not acknowleding the cancellation and still debiting my account. When I call in they tell me I can't cancel the debit order on the phone and that I must send a form or cancel online. The online option didn't work and so I sent in the form but obviously that didn't work either. Their cancellation email address doesn't work and so I have to email one of the Call Centre Agents who says they will forward to the relevant department. I still haven't heard anything from Telkom and in the interim they are *******ly debiting my account and I sit with the bank charges when they debit my account 2-3 times a month! How unprofessional that Telkom can't even have a proper process in place to cancel a service.