Say, just say, you ordered several items from a well-known mail order company, let's call it Vext. Say one of the things you ordered was a T-shirt for your 2 year old, costing less than a fiver. Say, when your order arrived, the invoice showed that you had been sent and charged for said T-shirt, and there was a bag with a sticker on it appertaining to said T-shirt. When you opened the (theoretical) bag, however, instead of a cute T-shirt it contained a rather nice pair of wide leg, navy blue, linen trousers, costing rather more than a fiver...in your size.
Well, just out of interest of course, as this is purely a "what if?" scenario..what would you do?