It's good advice that Matthew chooses to avoid. It is worth repeating.
Tony has highlighted good information from Which?. That's fine. All Matthew needs to do is write to Amazon, pointing out his rights according to Which? and he will get a full refund or a new product (his choice I guess) and all will be well.
Somehow, I think the Which? route will need the back-up of a decent solicitor to implement. I don't know why I think this, but somehow, based on Amazon's responses to date, as reported by Matthew, I doubt that a single letter to Amazon will resolve this matter. But worth a try.
Which? advice + Crime Number (which Matthew already has) = Success (let's hope)
(but I would pop down to the local nick and add that last, teeny, weeny little bit of input that Amazon has asked for........)