Harassed by Telkom

I have cancelled my account with Telkom in February as I was not getting the service I paid for. I paid my last invoice in April. To date I still get SMS 's as well as an account every month. Each time it's a different amount. My phone and ADSL was cut off in March already. I've written numerous letters to the accounts department to no avail. This is nothing short of harassment and incompetence. What to do?