Had stuff stolen out of my vehicle, while it was ...

Had stuff stolen out of my vehicle, while it was in valet care. Been fighting a claim for over 11 days now. There not wanting to be responsible for it. There was not forced entry to my vehicle or any damage. The parking attendant, left the gate unattended, which allowed a unauthorized vehicle into the garage that just happen to park by my truck and take things out with damaging anything. Nothing else was messed with in the truck. This vehicle stayed lost in the parking garage for over a hour, before exiting. No one once this vehicle in there.