what does it say in your bill of purchase? does it say something like: sold as is..? Try to talk to the seller first and you may be able to get some money back, if you are lukcy. Nerve buy a car from an individual without checking the history of the car. It is risky.
Do you still have the safety check certificate from the seller? If so, when was the safety done?
If it is not sold as is and the safety check is still valid (within 36 days), go to a garage and do a safety check (sounds it won't pass. The garage will give you their working sheet). Then go to the ministry of transportation and present an officer the safety certificate and the new safety check working sheet. Tell the officer that the safety check done by the seller was cheating. The garage and the mechanic who did this will be in trouble. And you may get your money back.