Advice from a frequent traveler, ignore your temper and smother with kindness, a smile and even compliment the biggest jerk/agent in the world. TMI: Once in AMS (Schiphol) on time for my hour flight to Brussels on what was Sabena (Such A Bad Experience Never Again airlines) after waiting 10 minutes in one of two long lines, as I approached the agent she said cheerily "be right back," returned 10+ minutes later, looked at my ticket and said nastily "You are too late to be boarded, next". My guess is she had a fight with her husband during the break, or other bad news - anyway, I took a train. Taking the escalator down a few floors to the AMS train depot, boarded the first to Brussels sans ticket. I told the conductor my story and he asked if I had 5 EU which I'm sure never made it to the railway. We've all had it happen.
Thank you for your comments, much appreciated, but I was traumatised at Schiphol, and yes I sound like liberal “victim”, but that is what happened.
I feel like Ben Carson defending myself.