Terrible customer service

I bought a pair of black shoes from Zara yesterday and when I arrived home I realized they were actually too big. I went back the next day to the Sandton Zara with my slip where they refused to take them back because they had been "worn". The manager John refused to help me and walked away when I was explaining I had them for less then 24 hours and that it was impossible for me to have worn them. I'm very disappointed in this as I'm such a loyal customer and really support Zara locally and when I'm overseas.