How do I deal with trolls in ranked?

It's probably most likely they won't get banned, and it's just making my lp drop hard. I mute them, not say anything. So they go afk and replace all of their items with Tears. It's almost impossible to come back from a game like that. It's so frustrating having to deal with trolls that go afk and just sits there and types random toxic comments. Most likely they could get a warning, but they're not going to stop trolling like that. They'll keep trolling and ruin more and more games. It makes League games just not enjoyable. Even if they get banned, it's still probably not going to stop them from their ways. They'll wait till the timer is over, and they're gonna go back to ruin more games because someone is having a bad game, or they just don't care anymore. I just feel like there should be more harsh punishments when it comes to people that are purposefully trying to lose the game so their teammates can suffer.