I have suffered from bargers and damage was done; took 8 months to sort out because the boat ABOVE ME did not apply the following rules-of-thumb and so then had to let the barger in and in the process damaged my boat

1, make it clear EARLY that the barger IS NOT GOING TO GET IN. I would suggest calling early (30 secs to go); "Hey <insdert sail number>, you will not get in here; I will take you high; you have no rights, there is no room"
2, If they continue..call them up again
3, "I am luffing in 5; you have no rights
4, 1,2,3,4,5
5, UP-UP-UP; you have no rights; I will have to alter course to AVOID you as you are barging in 3 seconds and I am counting down
6, 5-4-3-2-1
7, I have had to take avoiding action; protest.

I had the situation where the barger came in at speed and the boat above me DID NOT shut them out; they then sailed into me to avoid the barger; I could go no-where as I had boats below me and so there was a crunch; I was out of pocket for 8 months while it was resolved.

sailng can be hard when people don't know the rules.....

In summary

1, make it clear early that they are barging and you will not let them in
2, count down out loud so those around you can hear you
3, make it clear they will be breaking rules
4, PROTEST TO MAKE SURE THEY LEARN.