I've gotten the "couldn't duplicate problem" line on many of my dozen or so trips. So far they've always acquiesced after careful, detailed explanation of it issue.
Since this one required somethinking about how auto climate control should behave, including taking into account factors like outside temperature, sunlight, etc. I was not optimistic initially that an admission of fault would be forthcoming.
In short, I have little faith in their willingness to work on"non obvious" problems.