unfair business

Yesterday I went to the mentioned story buy a pair of boots when I got home the shoes were too big so I went back to the store to tell them that wanted a size3 not4 I was told they don't size 3 I said to them look around your other branches I don't want the money I want the shoes you can take your time I am not in a hurry I was told that all their stores don't have size 3 so I asked for my money back because they can't help me. I paid R699.00 for something that I am not even going wear the shoes are big. Please assist