Telkom service and consultants is really bad

I had a telkom account for a smart TV and a router which was due to be closed in November 2017. Like wise I went to their outlet in menlyn and I closed the account. The account was closed and no debit orders were going through from November. In April of this year they debited R420 or so from my account and I reversed the transaction due to not knowing what the money was for. Called telkom a number of times trying find out what the money was for and none of the consultants could tell me what the amount was for. All they kept on telling me was that my account was closed as I have requested. I then got a SMS from one of their credit collectors saying I owe telkom with any communication from telkom side. I paid the money still without know what the money was for and currently have a default listing on my credit score.