Hi Antonio,
You may find that CBS do not handle matters between a consumer and a private seller (which is the case here). I would suggest in the future, to have a look at the registration papers first before signing any contract and making payment. This is because, sometimes, the purported owner may misrepresent that they are the true owners when in fact, the car was stolen. Of course, here, you were misrepresented, but the misrepresentation could be much worse, so do check all details beforehand.
As to what you can do now, figure out what the difference between a 2007 and 2008 model is, monetary wise (difference in insurance premiums may be a start). Figure out if this difference in years is a big issue for you and would be something you would cancel the contract over if the seller refuses to compensate.
1. Negotiate with the seller and ask them to compensate you for the difference due to the misrepresentation. Note that he may not have intentionally misrepresented you so try not to accuse him of this out of good faith.
2. Your other option is unfortunately litigation. As Sophea pointed out, the Magistrates' Court is a good forum. You certainly would have a case here. However, the amount in damages may be reduced according to the amount of responsibility you bear in this matter, which is failing to check the registration papers before purchase. You may mitigate this reduction if this was your first purchase through a private seller and you have little experience purchasing cars, or that the seller was in a rush and gave you little window of opportunity to decide.