Mate that's rally crap, such a bloody shame.
As Iain says though as a last resort, you can advise that you will name and shame from a " moral" point of view.
Did you sign for the vehicle on the dealers premises.
If you did then the dealer is within his rights to keep the deposit, having said that you can put it in writing to him that you had changed your mind due to unforeseen circumstances ( I.e. You didn't know you were going to be made redundant) and that you will use free legal services to fight for your deposit as you need it for your family due to being made redundant,me specially so near to Christmas, and that a local journalist you know has asked you for the story as they are doing a piece on unscrupulous traders.
Put it in writing first, and ask diplomatically for him to reason with you, also depending on the amount of the deposit ask him to part refund the deposit for honourable reasons
If this fails then ramp up the pressure re journalists etc
But keep at it and you will probably get your deposit back
IF YOU SIGNED FOR THE VEHICLE OFF THE DEALERS PREMISES ( I.e. He brought it to your house go show you, or you gave deposit over the phone
You then have cooling off period and a right to your deposit back
Mate things will get better,