How to stop your team from throwing?

So I am currently in Silver 3 after dropping a bit here and there. I noticed a gigantic pattern in games when we were ahead and end up losing the game. Someone either decides to try shot calling in the chat or in their brain without telling anyone. This almost always ends up in bad fights that lead to the other team coming back from what seemed like an unloseable game. I was wondering if there are any tricks to encourage teams to not throw. Any help would be appreciated as this has been a common continuity every single time I go on a losing streak other than the obvious feeders and afks.