@Riot, There is a specific player who INTS my games every time he gets in my team. What can i do?

The elo is master-challenger. The player base here is so low that we know 80% of each other in our games. He claims that i trolled him in 7 games (we didnt even play 7 games together, just 3, and we just lost. ofc i didnt troll. he is just a tilter and flamer kid), and now he said im on his int list. And we now played a game again, and he was in my team, and even if we had free win, he lost it single handedly. Well now, i know riot wont ban/punish him because they hardly punish those who end up with scores like 0/20 by turret diving, while this guy makes the exact play to single handedly lose us the game. In this high elo you dont have to feed to lose a game instantly. Just by engaging 1v5 at 25' for example is enough to end game, no jk.

SO, its frustrating for me. I even tried to add him to see when he is in queue to try and dodge him, but he won't accept... idk what to do.