A Chinese airline's staff has come under fire for telling a passenger he'd treat them "like a dog." The passenger said he was in Singapore and checking into a China Southern Airlines flight. The carrier apologized for the incident, and said the staff member was employed by a local agency. Morning Brew Insider recommends waking up with, a daily newsletter. Loading Something is loading. Thanks for signing up! Access your favorite topics in a personalized feed while you're on the go. download the app Email address By clicking “Sign Up,” you also agree to marketing emails from both Insider and…