Sheet Street account

Last year in March/May 2017 I paid the full balance of may account with Sheet Street.

A couple of months later I was called by them to say there is R200 outstanding on my account, I asked them where this came from and if they could see that I had settled my account? To which they answer they could and that they(the person calling) could not see where the amount came from.

They called again in December 2017, where I told them that I had paid my account in full and that if they could tell me where the outstanding amount came from I will pay it. She could not tell me , she then also put the phone down.

Now I am getting emails and sms messages that my account has been traced for legal action when no one can tell me where the money that is on the account comes from seeing as I settled it and they said they could see that I had.

I will never by anything from them again.