car finance query

[jnic5]

hi all. i bought a car 6 months ago and it had oustanding finance on it which when i went to collect the car the person i bought it off paid it there and then on the phone and then i owned the car basically. now ive come to part x it in and it still owes money on it. the agrement was took out in 2004 but the people i bought it off only got it in 2006. i managed to contact them and they had no idea about this other finance as they bought it from a main vauxhall dealers. anybody no what i can do as i want to sell the car but can i. i contacted the garage and they said there going to look into it but its been a week now so just wondering can any1 advise me what to do