If legit means don't work, play dirty with them too...take something that belongs to them of similar value to your deposit. Tell them you'll give it back when you get your deposit back or the salesman honors his promise. For instance, go when the place is closed. Jack a car up, take a rim or two and leave the car on concrete blocks. Hold them in your garage. Make sure they don't get damaged/lost/stolen

If they call the police, then you should call the police too. Explain the situation and that it's a civil dispute. The police won't touch it.

The dealership will eventually want its "computer/rims/tools" back. Never damage anything...just take it and hold onto it until you get you what you want. Just make sure it's dealer property not someone's personal property.