Telkom wants to blacklist me AGAIN!

I am very disappointed with Telkom because I have been trying to cancel my telkom account, filled in all the information, and they still billed me incorrectly, and now have lawyers calling me all the time for money not due to them. I have proof of all my emails, that it was submitted in time, and they still got it wrong! I am even too tired to answer my phone because who ever I talk to just sits with blinkers on wanting their money, WITHOUT connecting the dots. This is the second time it happened to me. The last time they were again in the wrong, why why why why?