Unfortunately for you based upon the facts that you have written, you do not get your $500 deposit back for the car that you took possession of just because there was no finalization date for the transaction. In essence, you received the car on March 24, 2012 and had possession of it.Under the law regarding automobile purchases, unless the written agreement states that you have a certain time to return the car, you are obligated to continue making payments on it if financed, or if purchased in whole, you are stuck with the car unless there is a basis for you to cancel the contract such a fraud by the seller.You may wish to further consult with an attorney that practices in the area of automotive law concerning your matter.