Sounds like the typical dodgy cheque/ bankers draft scam where you cash the cheque wait for it to clear then refund the "excess payment" only to find the cheque bounces a few weeks later and you are out of pocket and the criminal has just made some money and had your car.

I still don't understand how a bank can "clear" the funds with a dodgy cheque or draft and then take the money back off you. You would think that the banks security measure are such that the cheque would bounce and if not then it is a failing of the banks security measures and hence you should not be liable.