Making ban notification for players that report always appear.
I've heard from riot once (in some forum I don't remember where) that when a player is banned, those that reported them won't always receive a notification that the player is banned. Next is only my conjurer, but that you'll only eligible to receive that notification if you where just in a game with them and are not in a queue. And I am unsure if you meet these two point if your guaranteed to receive one or not. Moving on but I thing a reason behind players viewing the report system as broken, and even the reason why players are toxic is because you cannot see they system working. So why not make it so you always get them. If you see it in action it looks like it works, if it looks like it works players will respond by being less toxic (because they know its in place). If you want to be sneaky about it you can even have fake report, thou I feel its only a matter of time before the fake is discovered. And in the case the player is for any reason unavailable for that notification, put it as a message. When they load in they can see it, keeps it out of the way so as not to disrupt you if you're in queue. And above all it make the players recognize it.
EDIT: Just had a perfect case where the duo decide to afk cause we didn't ff, no punishment or at least no notification. They just tapped tapped the mouse every often so they didn't get flagged.