JJBirish's post is almost assuredly correct, unless there is a whole lot more information we are not privy to, like you told them (in writing) that the valuables were in the vehicle, and they specifically (in writing) told you they would secure the items. The proper course of action is get a police report which you then send to your insurance company and they will process your claim. If the items have high value, you are going to be out of luck because the limits of your homeowners or other policy are going to have exclusions specifically to keep people from saying their $39.00 Walmart special guitar was actually a 1957 Fender Strat previously owned by Jimmy Hendrix. And just because someone allows you to park or store your RV somewhere does not make them liable for damages and losses occurred while you were parked there, contrary to what some of the posters here believe. I am sure the shop is well protected with the appropriate disclaimers and releases to prevent any such liability. It is pretty much boiler plate law.