You should never walk out without the signed contract at the time of signing. It gives them too much opportunity to make changes to the contract.
Those named dealerships should be more upstanding, but they aren't. The only person that is going to look out for you is you. The F&I guy gets extra pay to stuff in those add on's into your contract. The warranty and the useless "maintenance plan" are high-profit items for the dealership and the F&I guy (both).
Call the lender. Tell them about the cancellation and send them a copy of the warranty cancellation. You want to follow up with them to make sure the dealer actually cancels the warranty and the funds are credited to your account. It wouldn't be the first time if the dealer canceled the warranty and failed to credit back the funds.
Same thing with the "maintenance plan". These are the worst plans around - you pay in advance and they typically honor for an oil change or two and then don't follow through with the rest. You can read about the plan failures all over the net. It is especially easy since you have no paperwork to prove it (step #1 of the scam). If the intent were to actually follow through with the services, they would give you the written contract with the terms for the maintenance plan detailing what is included right up front and not sneak it into your purchase and sale contract without your knowledge. It is mainly there to increase the profit of the dealership and the pay of the F&I guy.
