Disappointing service

I am extremely disappointed with the service received from Mr Price Chris Hani Mall. I sent my little sister to exchange items that I purchased a week ago as they were too small. She had a slip with her and the clothes still had the price tags but she was turned away!! I am not able to go myself as I have a one week old baby. The lady assisting her was rude and told her that because the items were bought with a card she is not able to assist. Which is a lie because I have been assisted with returns in the past and was never told such! After this experience I really do not see myself buying there again. I cannot leave my small baby at home to be sorting out such ridiculous issues. All I wanted was a bigger size on the clothes and chances are that by the time I can get a chance to go the store myself all the sizes will be done. I have a good mind to take back all the clothes that I purchased that day which amount to R2000 and go to another store that values clients.