Double billed

On the 26th of october I credited two items. The amount was R580.00. Today when I received my statement it shows that I made a purchase of R580.00 and then a credit of R580.00 on the 26th of october. I only bought a dress at menlyn branch on the 26th of R250.00. I wanted to credit my items of R580.00 which I bought at kolonade branch on the 30th september. When I called the call centre they say I have to go to the branch. Why is Identity making their mistake my problem. I want this to be rectified as soon as possible. Why would I purchase and credit at the same time.