Bill of sale help.

[hand77]

What is the name of your state (only U.S. law)? Tennesse

Ok here's the situation. My cousin purchased two Volkswagen Golfs, a 1995 III, and a 1997 VR6, in mid June. He purchased them both for the amount of, $3650. The 95 being $1795 and the 97 being $1855. He drove the 95 home that day, the VR6 had to be sent off to a local shop for a new head gasket. Here's the problem. They got a bill of sale for the III saying, $1795 for the car, tax, tag, doc, etc. And a receipt saying the $3650 had been payed for the two cars, paying them both off. The owner of the lot then took an "extended" vacation. He finally caught up with him this evening and went to pick up his car. He gets there and the owner says he still owed $1300 on the VR6, thus bringing the total out to, $3155 for that car. The owner signed and dated a bill of sell for that amount. Here's my question. If they have to take this to court who's to win? He (my cousin) has a reciept stating $3650 was payed in cash for the two cars, and a bill of sale stating the price of the III, both being signed and dated on the same date? Thanks for the help in advance