[NeedAdvicePlz]

Jan. 12, 2005 on my birthday, I purchased a 99 Ford Contour Sport 5 spd. with 127,000+ miles for $1800 cash. The same day, my check engine light comes on, on the 14th of Jan. it was taken to my mechanic who had told me my catalytic converter was running under thresh-hold, bad enough not to pass inspection, I was given a bottle of Fuel Emissions Test Passer to include next time I filled my tank, i was instructed to inform my mechanic if the light had come back on following the inspection, it did the next day, Feb. 3rd is the next time i got it into 128 Ford for a diagnostics test, results came back that 2 of my converters needed immediate replacement, one other was a strong possibility, which brings the tally of all my converters needing repair, I informed the seller of the vehicle of the problem he immediately bounced off the walls telling me that my father and I who accompanied me in this endeavor were horrible people for taking advantage of him after I had asked if he wanted to make the repairs of 1500 - 2000 dollars or if he wanted the car back in exchange for my purchase fee, he declined my advances to resolve this situation, now im stuck, I need to know if he's liable for the repairs and if I still have a chance at not getting shafted, I need input asap... since the purchase I have put 800 miles on the vehicle if this info is needed and still 9 days under the purchase date, please help me...