I am going to reply here because this is a safer place than GD. Yes, I work in a car dealership in VA, I work in finance, I know the type of dealership that Passport is and I think I might even know your finance guy. Is his last name Dadpay?
Here's the situation. You signed a "MacArthur Statement." Its also known as a "conditioned contract statement" or a "courtesy delivery" form. Essentially, it says the contract still must be approved by the lender. If the lender does not approve it, you have the option of retruning the car or arranging other finance terms. It allows the dealer to let you get in the car before the loan is approved and allows you the ability to make a decision immediately. Ethical dealers will not let a car off the lot if they don't have a pretty good idea that they can get the loan approved.
What likely happened in your case has to do with negative equity. Did you owe more on your old car than it was worth? If so, that may have pushed the total transaction price above what the bank will normally accept. If your FICO score is close to 700, the dealer probably figured they could get the loan approved anyway and let you take it.
Now, the 10 day thing is a pile of crap. When a deal is turned down by the bank, we often "rehash" it with them. We'll go back and tell the bank why we think they should let one go. More often than not, we can get these done. Sometimes we don't, but it usually only takes a couple of days. We want to get it straight as quickly as possible because the longer you have it, the more miles you put on it and that makes it harder to sell later.
Now for the good news. If you do decide to keep the truck and you put the additional $700 down, its not like you're loosing $700. The loan will be recalculated with a new and lower principal balance. You're payments will be lower as well. The $700 does not go towards dealer profit in any way.
The bad news is, you don't have a lot legal options. Ethical or not (and its not in this case), they have the legal right to do what they did. You will spend a lot more than $700 on legal fees, only to be told you have to return the truck and they will give you your car back.
I wish I had better news for you on this. I hope this helps.