Refusing to give credit note

I bought shoes at the above mentioned store on Friday the 20th of Feb 2015. I wore them on Saturday for a function. I had been sitting for a while and when I stood up to have lunch, I felt that the shoes were giving me a burning sensation and were not comfortable, especially around my toes. After the function, I walked to the car in the unbearable pain that the shoes gave me. I took them off and drove home. I decided that I will take the shoes back to the store. My sister works in the Pretoria CBD and so I asked her to take them back to the store on Mon 23 Feb 2015. My sister was turned back by the Supervisor (Mr. Gicshka) because he said that he couldnt accept the shoes without the original receipt (I forgot to give her the receipt). My sister then went back to the store the next day with the original receipt as requested Mr. Gicshka. However, the Mr. Gicshka refused to credit my account and said that the shoes had been worn. My sister explained that yes the shoes had been worn but only for a little while because they started to hurt my feet. She explained that I can no longer keep the shoes and risk further injury to my feet. Mr Gicshka was not concerned and blatently refused.