They don’t deserve your money – get your deposit back (they have no right to keep it, given that they have not yet placed your order), move on and take your business elsewhere.
They’ve played you from day one when they’ve taken a deposit from you and not even given you firm written financial details of an agreement it is expected that you will be entering into to finance your new car. That might actually be illegal as per the regulations attached to financial services, because they’ve actually taken a deposit without giving you a clear and written indication of the cost of goods and the cost of the finance (interest and other charges) over the term. Would you allow a double glazing salesman to do this to you?