I had something like this happen with me at Ford. service guys said they couldn't find anything wrong with it. I videotaped it, ran into the dealership and demanded the service manager. showed him the past visits, video and gave him an ear full. Amazingly he went to my vehicle -- looked at it and in 1 minute he figured out what was broken. Grrr I was looking for a big battle.
my 2 cents:
Video record it a few times.
Then park it at the dealership the night before a cold weather snap that would exhibit the issue.
Then the next morning, first thing, personally have the service manager watch the video then have him come out to the car... show him the problem live.
2017 Burgundy MKC AWD Reserve 2.3L 20" rims, Tech Package, Climate Package,