update on credit bureau

I have paid up and closed my jet account in 31 October 2014. When my account was paid up I overpaid with an amount of 500. Jet stores agreed to refund me the amount and deposited the 500 back into my account. surprisingly when i check my credit bureau status it says I have been owing jet stores 500 from October 2014 which I don't know about. I have called the edcon customer care a million times and all of them come up with excuses. This is damaging to my credit score and profile