Returns

I won a voucher on the Foshini Facebook competition. I then went to make a purchase. When I got home I found that the sizes that I took were not suitable. I decided to go make an exchange. I was not assisted. The manager was called twice to assist since the items showed a different price when scanned. The first time he said the exchange will not be possible. The second time he said to me \why did I buy those items in the first place". He was rude. My question was since I'm not happy with my purchase. Should I be stuck with these items? Just because they were bought with a voucher."""