How to manage my scrub friends?

They are all hyped about doing 3v3 ranked, but gosh are they bad, like so bad, and every time i try to tell them calmly of what they couldve done better, but all they seem to do is complain about how x or y champion is op, and the cycle repeats the game after with them banning what rekt them last game...

Its getting really annoying.

What can i do, because i'm on the verge of ragequitting this now.