Agree with the above - Let the Police know all. At the end of the day how would you feel say if someone Stole your car, sold it to someone and that person found out it was pinched and took it back for a "Refund" and then withheld the name of the person who it was purchased from?

Your just letting someone get away with theft (Not specificaly the person you purchased it from) and letting them do it again.

Apart from that How are you going to explain to the police "I took it back to the Pub for a refund"?