Ford

I have a 2018 GT Premium that I bought from a dealer in Osswego Il. in Feb. of 2019. I stopped at our local ford dealership to inquire about an intermittant issue I was having with the left outside mirror trying to move on its own when the switch was in the off position and when I closed the door. The first question the service master asked me was if I bought the car there. When I told him no, he told me to take it back to where I bought the car. Doesn't Ford take care of warranty issues at any ford dealership? Needless to say I was very perturbed at the way I was treated by this individual and when I left I had a rotten taste in my mouth never planning on darkening their door again. I have always had my ford truck and other mustang serviced there before but not now. As I have inquired about this issue and got no satisfaction from mack ford, what is my next option? The service managers name is Mike Paulson. Thank you for any help. A forever Ford fan until now.