I recommend getting into further conversation with the person in charge of the valet staff or the hotel manager himself. See if they can nail down who actually parked the car or who had key access through the night. Then ask if they have had other theft complaints when any of these same people were on duty. I was getting no where with a hotel when I had $400 cash stolen from my room during housekeeping. They gave me a credit within hours after I asked them to take an honest look at the problem. I think they realized they had a pattern and had to make good. (and get rid of the thief). They might not make good for you but the next time it happens someone else may have more success because of you.