i would insist on full refund and you could try to get some of costs out of them, yeh you have had the car for a year but how much has it cost you, not to mention the hassle of now replacing it.
Did you happen to catch RTE's Prime Time- Investigates about 6 or 7 months ago. They went through a few guys in the motor trade for a shortcut. Named and Shamed, it was excellent tv. But they also showed how easy it is to clock cars and that the market is full of them.