Return Policy

On the 7th Dec I was @ Pep Newtown got attitude from the staff left the store, On the same day went to Pep The Glen wanted to exchange something which my son got as a gift, The items was way to big for him I don't have a slip however the barcode is still on the items. I asked for the item to be returned for something else in his size and was just told that no that's against out policy like who created that policy? why cant you exchange items for smaller or different items it its still in the same packaging?