Poor quality

I bought a shoe at Rage, I fitted the shoe and it was good. I wore the shoe once but I didn't last long on them because the quality of the other shoe was bad,it didn't fit me well which it was confusing because it was the same size shoe. The right shoe fitted me correct and the left shoe didn't fit me well ,so I'm guessing that the gave me a shoe which was fitted before. Today I tried to bring back the shoes but they refused to help me saying that it is not their fault, Palesa Tuja(manager) also refused and told me to just escalate the matter if I want to. I'm very disappointed because it was not my fault that they gave me shoes that was fitted by a customer which led them to being a poor quality,thank you .