So someone used the overhead space. So what if your briefcase wasn't easily accessible during the flight. If you needed something, you could have just moved the other bag and get to it. Deal with it. I think that all of your whining and escalation of the issue was pretty unacceptable behavior, much worse than that of the person you are complaining bout. It is like kindergarten behavior -- teacher, his bag is touching my bag! You were offered an alternate solution by the FA, but you wouldn't take it, because everyone was going to play by your own rules that you made up, and until they did, you were just going to escalate it further.