I can't speak for YOYO Tech as I've never used them. One company I can pour praise upon is dabs.com they have never failed me. Although there was the one time when DHL delivered an order from them and decided to leave an expensive (at the time) 5870 graphics card on my front door step! That's just DHL though! It's just a pity that they don't have quite as many toys as SCAN and offer quite the same service for sales and deliveries. I do like DPD and the free postage is fantastic. It's an imperfect world, I guess I can live with that as long as my plastic got my back covered!
Under one year taking "use" into account instead of offering full money back. But when you're selling with as narrow margins as these guys are I guess you've just got to appreciate the other aspects of their service :-/
You can claim 'damages' which under the eyes of the law is the cost of replacement or repair of the goods. Also something else that surprised me is that Section 75 under use of a credit card applies for 6 years!