No one is in the wrong really as it is very very common for early model bikes to be put on a later plate. But when they are sold on the later plate they are still brand new and considered that reg bike so it’s NOT a 2 year older bike you have it’s an early model 2008 reg bike. I just bought a 2007 xt660 but did not notice it was a 2006 till I got it home (02 sensor missing) but does that take anything away from the bike NO .it’s still a 2007 bike and will be sold as a 2007 bike when I sell it,as that is what it is. I also have a 2015 Fz1n and I bought it at one year old thinking it was a 2015 model I got the belly pan painted and the paint code was from a 2010 bike so the bike in fact is a 2010 model again does that make any difference NO it’s still a one year old bike and is still a 2015 plate bike So I would say get over it and enjoy your bike. You liked it when you bought it. So what’s the problem. And bottom line you don’t have a leg to stand on. Just ride the thing and stop trying to get money back apart from the 02 sensor it’s the same bloody bike. The shop sold you a 2008 xt660 and that’s what you got. It maybe an early model but it’s still a 2008 bike and the age go’s from when it was first registered so when the bike was sold in 2008 the bike was not sold as a 2 year old bike it was sold as a new bike and it was.and just so you know I had a 2011 bike with all the mods and the bike still cut out from time to time at speed when dropping down a gear bloody dangerous but hay the xt660 you love them or hate them. If you like your bike just enjoy it the bike was not sold dishonestly the bike was sold as a 2008 reg and it is.