Just thinking about this from a different prospective, let's say you mot, service, pdi, replace everything that you buy/sell the additional cost of that work is it greater than what it would potentially cost you if you had to refund the odd purchase. In reality how many cars are returned for a full refund ? The sales of goods act has always been present and although it's been tweaked some dealers still didn't meet there obligation under the old act. I know of 2 incidents at our place, one we gave them there money back and the other we refunded them then had to replace the clutch and dmf and then they purchased it back from us. I know from being involved in mail order at my last company just how difficult people can be they read the Internet and listen to the to and they suddenly think they know everything. I have helped more people when they were honest than people who go on the attack straight away, like someone who's dog chewed a product, he got a free replacement as he was nice compared to a customer who claimed there product didn't work but forgot to say they had dropped it in water.