Telkom Service and account department bad service

I have a big problrm regarding my account at telkom. I have cancel my subscription last year 13 July2019. I got a case number ***2. After a couple of days I received a sms that it was resolved. Thought that was it. Then about a couple of weeks ago i got a invoice for R1900. I phoned again on why this is. Then the agent say it was never done for some reason and he will log two calls to make the account R0 again and then cancel it again. I received a sms ove both the calls that it is resolved. But now again I received a invoice for service and subscription. This is really not good service. What can I do.