Never take a spot delivery. Many times the dealer knows the buyer will not be approved for bank/regular financing, spot delivers the vehicle, then weeks later calls and says that financing was declined to customer has to sign a new contract which of course will have have some/all of the following, higher price, interest rates, fees, etc.
And sometimes they even say or actually did sell the trade in.
Read your contract word for word, does it have a contingency clause regarding financing? If they at all balk at unwinding the contract with no cost to you, simply say OK let me think about and I will call you in few days. Then immediately hire an attorney and let the attorney call them. DO NOT say I will sue you, or I will get an attorney or call the BBB, or the state dealer association, etc. Just be polite, leave and hire an attorney.
Yes this will cost money, but it will cost less than getting stuck in a bad contract. They most likely did this deal on purpose will not make it right. Just my guess.
Best of luck.