I used to have a shop in town that stole parts all the time, from myself and others. The first time it happened to me I took my bike in to swap headsets, they took off the Stronglight Comp headset, I told them I wanted it back so they put it in a bag and I took it home and stuck in storage, 5 years or so later I took the bag out to use the headset for a project and turned out they put in a cheap Tioga headset. I heard other complaints from other riders since I discovered my problem.