Sissy boy worst exchange policy

I am extremely disappointed with Sissy Boy' retail system. I bought my daughter a pair of shoes for R700 on sale at Sissy Boy Victoria and Waterfront it is for Matric ball. My daughter had an ankle injury she won't be able to wear the high heel shoes because she's on crutches .I bought it back to the back and asked if I could take something flat and comfortable for her as I am unemployed and could not afford to buy another shoe ,Bronwyn Brown the assistant refused to exchange it and she was very rude with me, I left the store crying because I don't know what my daughter is going to wear or she will miss out her Matric ball because of worst customer service I got from Sissy Boy I will take this further.