The gold partis is the vacuum actuator for the manifold flaps mechanism. There should be a linkage between the actuator rod, and the flap spindle.
The missing part could be the bell crank that is fixed to the flap spindle.
There is also a potentiometer that monitors the flap position. It is part 17 in the exploded parts diagram.
Contact
@A2Steve or
@Clackers who may well have a spare.
It would help me be sure if the garage could take a pic of the parts they have, and where they are fitting them.
Once the repair is complete, the flap mechanism must be calibrated using VCDS, a software diagnostic tool. Please make sure the mechanic is aware that the FSI is very technical in it's operation, and unlike most, (if not all), similar VSG engines.
Mac.