Sadly car dealers are car dealers, sometimes information is not passed on due to ignorance, sometimes deliberately. Hopefully it was a mistake in this case not a deliberate attempt to hide the truth.
If they are a reputable dealer they should negotiate an adjustment in price to reflect the actual year the car was manufactured. They won't pay "compensation" as it's an admission of guilt. However, an adjustment to the price saves face for both parties.
Good luck, hopefully you'll reach an amicable settlement without the need for legal action.
