Telkom is the worst service provider

Telkom is the worst service provide I have come accross. They obviously have *********** imbeciles as employees. We had an account with them which we cancelled in February 2018 as we upgraded to fiber through another service provider. In April we contacted them again as the debit order was still running meaning that they DID NOT do their job and cancel the account. They assured us it has been cancelled now but still month after month we have been billed. After numerous phone calls to them they eventually managed to cancel the account in October only but our issue is still not resolved. We have been on the phone with them once a week for the past month trying to get the credit sorted out for all the months that we have been billed in error and all response we get from them is "it hasn't been processed, we will log another query" and they promise that someone will get back to us within 72 hours and absolutely no one has contacted us.