Shoes

My heart is so broken. I went to Spar in Boksburg Commissioner Street yesterday. I bought 2 pairs of shoes and before I pay for them. I asked the cashier who was helping me if I can come back and exchange them. He said that I can exchange them. But I must have my receipt as proof. When I arrive at home. The shoes are too small for my twins. So today I decided to take them back to the shop. When I arrive there they told me that I can't exchange them. So I told the manager that I asked the person who was helping me before i pay if i can exchange them. They call the guy and he confirmed that he told me so. So the manager told the cashier(Thapelo) that is fine they can refund my money back but is he's lose. So I don't understand why he has to get a loss?Because they have their shoes back and I have my money back. I'm not happy with their service.