Well, I have to say, they would, wouldn't they ! They just can't be bothered, but they who the contract has been formed, so are liable.
"Which" do a really simple guide to the Sale of Goods act, or you'll find lot's of easy to understand help on it if you google it.
Firm's will try to evade their responsibility, unfortunately - and often they can't be bothered to learn a bout it, probably because they find it easier to fob people off.
Oh, see your PM's.