I volunteer for a charity and am dismayed at the number of people who ask for a discount on their purchases and can get quite abusive when refused. The charity needs every penny to provide their services. They wouldn't ask for a discount in the supermarket or stores like M&S. Would you ask for reduction on already reasonably low prices. Also there are times when the charity cannot accept donations because they have storage and if there aren't enough volunteers to sort and again some people do get abusive. Would you be expected to be treated with respect if you worked in a charity shop.