Better yet, can Hospital Security or appropriate body not tow the vehicle? That'd make it better, cleaning out your ambulance as he saunters back out to find his car gone.. "Oh, there you are mate. They asked me to give you this" and hand over the details of recovery costs etc. Vindictive? Me? ..er, probably. A career in Customer Relations (read: being whined at for a living) does that to you. :D