Return issue

I have been a Miladys client for the last ten years..never had a problem. Last summer bought item and have never worn it...still has all labels etc on...however do not have the slip for the purchase anymore. Gone through my closet this morning and decided to return the item as it cost R449.00, would take something else in its place...however without the receipt they are unable to exchange the item and they are only able to refund R29.00 as it is marked down? I accept it is my own fault for buying an item I didnt wear, but how is it possible that an item's worth can go from R449 to R29 in a couple of months?