Bad Communication!!

I cancelled my medical aid with discovery late 2014. I was subsequently informed I owe discovery a fee of a little over R100. Without asking any questions, I made the payment. After a few weeks I received a reminder of payment, so I called to find out what is happening because I've paid them. I was then informed that I was given the wrong account (Vitality account), and they can see the payment in the other account, which can easily be transferred. I then took down an email address and asked to receive confirmation of account closure once they have done the transfer. I emailed numerous times, however never received the confirmation. It then came to my attention whilst changing jobs, that I now have a bad credit record, because Discovery decided to blacklist me for R100!! with no further communication about me still owing them money from their side, or final warning explaining that they will now tarnish my name for a negligible amount that I have had to keep checking if they have transferred correctly because they couldn't be bothered with popping me an email, or the lovely messages they had sent to begin with!