you need to determine if you had a bailment agreement, and what the bailment agreement says…
you will need to show that the lot owner was not exercising reasonable care to prevent harm from happening to your vehicle… and check the states laws on Hold Harmless Agreements…
Hold harmless agreements are another way out of paying for damage for auto mechanics and repair shops that want to push the coverage for any damage to your vehicle back to your policy… A hold harmless agreement states that you will not hold the auto repair shop liable for anything that happens to your car while it is there… Once signed, a hold harmless agreement, which can be as small as one or two sentences in fine print found at the bottom of a repair agreement, releases the auto repair shop from any liability…
Rules pertaining to hold harmless agreements can vary depending on the state law. In fact, some states only require that shops post a sign saying "we are not responsible for theft or loss of property for vehicles left at this location" in order to avoid liability... Other required you specifically sign an agreement…
You will need to find out if the auto shop's insurance policy covers the customer's vehicles in its custody and control….
Now if accusing the shop or its employees of stealing in another subject all together…