Telkom cancelation.

I have been trying to cancel my account with telkom for months now and every month I get a new invoice sent to me. I have tried canceling on the web page and it doesn't work I have phoned numerous times and emailed numerous people with no luck. They can sign you up for something over the phone but you can't cancel an account with them. It needs to be done on the web page which doesn't seem to work. Seems like they do it on purpose to get more money out of people.