I need EDCON to please refund me what they owe me

I paid off my account I had with Edcon, and ended up paying over by about R260. I called in the call centre to close the account and I was advised that I had to be refunded as I paid in extra on the account. I was told to write an e-mail to [Email Removed] and send a letter requesting to be refunded with a copy of my ID, and bank statement which I did but the person never responded. The account has since been closed but I still have not been contacted for my refund. If it were me owing them I wouldn't sleep because of their phone calls, so what is so difficult for them to pay me back what is due to me?