Player dooming us to failure before the match began. Tilts whole team into surrendering

Hey so i got this Leona in my game who doomed us to failure because mundo got through pick/ban and ended up on the enemy team. The game started and he began flaming before the minions even spawned. I went ahead and muted him, though i could see my teammates responses to his trolling throughout the game.

I am playing Lucian, i'm 15-5, and we get aced in a teamfight. its about 25 mins and the surrender vote goes out, getting a 4/5 vote.

Naturally i was fully prepared to carry the game, but due to Leonas insistance and constant flaming, the team was too tilted and voted yes.

This upset me quite a bit, and thats why im making this post. Please do something to this Leona.