Cannot Cancel Landine and ADSL

Since 16 Oct 2017 I have been trying to cancel my Landline and ADSL account with Telkom. I have completed the forms and sent a copy of my ID book four times to different people. I have spent hours on the phone and sent around 30 emails and I am still being billed. I am concerned that my escalating bill will be handed over and that will get a bad credit rating. Surely terminating a customer should be a simple procedure. I have spoken to many people and have details of all my interactions. It is impossible to speak to senior management and the call centre does not work as you can never get back to the same person. I really need help to finalise this matter.