> the end-user has no real control over
End user has the same control as over any feature of the car.
If you buy Tesla and then buy FSD and then sell that car to someone else, FSD stays with the car. It would be absurd if it worked any other way.
In this case, the car was sold back to Tesla, a dealer bought it from Tesla and sold it to someone. Tesla determined that the car was configured with FSD even though the user never paid for it.
Now it's a he said / she said situation.
The user got screwed because he lost FSD that he thought he had.
The question is: was he screwed by the dealer (who mis-represented availability of FSD) or was he screwed by Tesla (who mis-represented availability of FSD to the dealer). Or maybe the dealer misunderstood.
Either way, this should be straightforward to resolve.
The buyer should be made whole by the dealer, because dealer sold the car.
The dealer should be made whole by Tesla (if Tesla indeed misrepresented the car).
All parties have relevant documents so it should be clear who's responsible for what.