This is just poor manners. If you had the frequency first the other station should respect that and move. Have had that happen on many occasions when I've been holding a frequency for a hour or more. My response is to just keep calling CQ and eventually the guy will get the message.
The other one the bugs me also is when holding a frequency and working stations as fast as I can, I'll get a semi-rare DX station . When I finish the contact, I will continue to call CQ but some rude operator will start calling that DX station, ignoring me.
This are other types of rude behavior which I suppose is because of the lack of proper mentoring both here is US and abroad. I sort of blame the "get your ham license in a weekend" mills which give new licensees just enough info to pas the test and to hell with the rest of stuff that they should know. Hope that stuff doesn't move on to the medical profession because we'll all be in trouble.
From: "randy true w4rttrandy@... " <070@...>
To: "070@..." <070@...>
Sent: Wednesday, November 1, 2017 7:52 AM
Subject:  another thing.....
Another thing that p--se me off, is the guy that will jump the frequency I have been using. Ten seconds after I end a qso.