for gosh sakes. It is a simple breach of contract. You bought the car. They have failed to provide the required proof of title within a reasonable time (as well there might be a legally mandated time period, haven't looked). therefor, they have failed to perform under the terms of the contract.
If there is a legally stated period they must comply, you might be able to demand a rescission of the sale right now (I'll let you look for the applicable law)
If there isn't or you don't want to look, simply send a demand letter giving them a week to provide the required paperwork or issue a check for the money you have paid towards the car.
If they refuse to provide the needed paperwork and do not have a reasonable explanation and refuse to refund your money, you can either proceed to sue them or contact a lawyer who will start with sending them a letter.