The dealer cannot keep your deposit.
I worked for a VW dealer in the sales dept and trust me, you can get your deposit back. they might make it difficult for you, because unless you pick your car up, all their work will become unpaid. The one that loses the most is the salesman, because he has just lost a sale on the board. The dealer can still sell the car but he will only benefit from that if he sells it again.
Simply approach the Brand Manager/Dealer Principal and explain your situation. He will not want to have a disgruntled customer and will simply tell the sales manager to refund you. (Trust me, this happens).
What I would say is don't lose sleep over this and if I were in your position I would spend more time securing my job than worrying about a car order.... ;-)