So you wasted time playing on their server, asked your friends to join, made new friends, etc etc, then the server turned to crap. Too bad. This happens all the time.
The server doesnt owe you anything, even on a donation server. Even if you helped the server out in your own way, it still doesnt entitle you for anything.
So the GM bans people left and right, so what? RO servers are a dictatorship, they own the server they can do anything they want. Even if you are the most active, most helpful, most whatever.. it doesnt give you a right whatsoever, or to make demands for this and that.
In the end, its always the players fault (ie. for playing on a server that turns to s***, getting scammed ingame, scammed from donations, hacked, banned, etc etc...)