Well, I once had a supercharging problem. Took it to a service center, and they did all sorts of diagnostics and were stumped. So they replaced every single component, from the chargeport, to the charger, to the high voltage DC boxes, all kinds of boxes, everything in the chain all the way to the battery -- including the high voltage cables. One by one they replaced these components, reinstalled firmaware, rebooted, took like an hour for each component, and several days to do the whole job, until they discovered the flaw. Which was in one component. They let me keep all of the other new components. I basically got an entirely new charging system, including new chargeport.
But they didn't give me any parts. I suspect they'd have been worth a lot of money. Hmm.
They probably let you keep all of the other new components because they were already installed and didn't want to spend days putting the old parts back in.
Did you pay out of pocket for the repairs or was it under warranty? If warranty then it's normal for them to keep the parts.