While "[the agent]" needs to take a chill pill, I am glad that F9 was so willing to accommodate you and you were willing to accept a free flight. I've never received bad service from F9 but UA is bad much of the time. It sounds like s/he doesn't want to work there and would be much happier working somewhere else. God help us if s/he goes to work for TSA but she'd probably fit in as US Air.