Thanks. Yes, I was expecting that ... however the car hasn't been at Tesla for nearly a week (its having some repairs done [to wrapping] elsewhere and was either driven there or put on a trailer from Tesla Service nearly a week ago).
I've contacted Tesla but the people on the phone implied it was impossible that it was still in service mode ... or that the repair people (who have no association with Tesla) would have put it in Service mode (I can't believe that they would have the ability to do that, or that the support person would think that was even remotely possible).
I just want to check that the battery is charged ... and tell the repair people to plug it in if needed, they probably aren't clued up on the need to check that ...
... hence was keen to know if the API error I'm seeing likely relates to Service mode, or perhaps something else (in which case Tesla would be right that the car is indeed no longer in Service Mode ... but I have some other, new, problem to solve
)