Better Business Bureau.

Also, you can review the dealer on Edmunds.com

 

This is seriously one of the oldest car dealer scams in the book. I'm actually shocked and amazed that an Infiniti dealer in this day and age would try and pull that crap. They stick you in a car, and give you a great rate. You drive the car around for a while and fall in love with it. Then they call you and say there was a problem and they need you to come in and sign a new contract. Of course its much much higher. They are counting on your emotional attachment to your new vehicle. After all you've had it for several days and fallen in love already.

This is an old, scummy tactic that I didn't even think was in use anymore. Except for at the "tote-the-note" style car dealers.