Angry customer

I went to Clothing junction in Dawn park just now to exchange a small dress and get something else but i was told that they dont have the dress in stock anymore and the price went down so they wont be able to assist me because they will have a stock loss because i have a slip stating how much i bought it, so the dress doesnt fit me what do they expect me to do with it,iam really not happy with their service. I mean they should come up with a solution..