There are a lot of questions here you should have an attorney examine. First, if the VINs don't match, you might not have a title to the car you're driving. If so, this will create great problems for you down the road. Second, sometimes accepting payment can limit your legal options--but that depends. You need an attorney to analyze exactly: how much you were paid, why, and what you knew at the time of payment.
(This statement does NOT constitute an attorney-client relationship between you and AKER LAW, LLC. If you need legal advice, you should consult an attorney).
If they returned 100% of your money, it sounds like you have no damages and therefore no lawsuit. But, this sounds like fraud and you might want to report the dealer to the Attorney General for a consumer fraud investigation: http://www.ohioattorneygeneral.gov/Individuals-and-Families/Consumers.