A few years back I had my Range Rover serviced. Two or three weeks later I popped the hood and found a large wrench like device in a cavity near the window wash fluid container. Called the dealership and they, as it was an unusual tool used only for a specific repair, immediately sent someone over to retrieve it.
The employee told me they had looked for it everywhere in the shop area as apparently it was an expensive tool, used infrequently so they only had one in their tool inventory.
The same thing happened to me when I had my Bentley serviced.;-)