Telkom refuses to cancel my expired contract

I have sent them my cancellation form so many times I have lost count. They say the attachment they cannot view, I have sent it in different formats from different email addresses, I have sent it to other people to test I it goes through to them and they are able to view it. The staff at Telkom are outright lying about not being able to view it they even refuse to give me a fax number to to send the form to. 2 years ago I have an email confirming that they received the cancellation form yet every month Telkom subtracts money from my account and everyweek I have to send the cancellation form through because they say the cannot view the attachment.