Telkom are billing me *******ly

I have been trying to cancel my landline for months and am still being billed. I have exhausted all options.

Everytime I eventually get through to someone they appologise and tell me the line will be cancelled and that I will be refunded for the months since I first submitted the cancellation request.

I have multiple reference numbers and emails.

I have to keep paying or it will affect my credit record.

What the **** am I supposed to do here?