They are probably trying to break the law though you need to get legal advise on this.Most car purchase contracts are signed subject to financing so they can get out of it if you can't pay but in this case it seems that they have decided they want to give you a different amount for your trade in. Unless they can come up with a damn good reason to lower the value they are just going to have to accept what they agreed to pay for it at first.A damn good reason would be you damaging the car between the time they valued it and the time you traded it in, if the reason they try to claim they lowered the value was because they found a defect in it then if that defect were there when they looked at it first then they are the ones who should pay for not picking it up.EDIT: If the person they thought should have valued the trade in wasn't there it's their problem, not yours.