Telkom not canceling my account

Twice this year I have needed to cancel services with Telkom. Twice they have sent me an SMS saying that my cancellation has been received and a cancellation number will be following. So one thinks that everything is fine and everything is cancelled as all appropriate actions and paperwork had been provided from my side. I tried to check on the app a few times to check that the cancellation had gone through, but half the time the app doesn't work properly so it looked as though the services had been stopped and that they had stopped charging me. I was quite prepared to pay 30 days cancellation, and then I paid for a second extra month, but now they have just sent my latest bill and they are still charging me the full amount. This will now be the third month of Telkom charging me for ADSL and internet services that I no longer use and am paying another service provider for. This situation is really unacceptable,