Poor service

I went to the store to exchange sum sneakers bcs they were having a factory fault.when i get there they ddnt have my size...they ask me to check another thing which i ddnt find.they offered me a gift card which it was cool with me.suddendly the is no gift card in the store.they say i mast come bac n collect the gift card.and i told them a going on holidays but still they ddnt make an effort. I called the area manager he promised to sort it out..afyer few minutes the assistance manager called me n insulted me.