Trolls are unbannable and it's really lowering the quality of this game

I keep getting bad game after bad game. I don't even know how people have fun wasting their time ruining a game.

I just had a smurf in my game (it was easy to tell by his actions username etc) on our team who just wanted to troll. After running it down 3 kills he decided to play the game but not contribute to the team. If enemies were near him he would attack but he was playing the game like he was in a bot match or practice tool. He wouldn't help us in teamfights. He would just go around farming camps push a wave and try to 1v3 etc and he was my support and didn't buy support item and just farmed.

We tried playing around his actions. At one point, he tried to solo baron and when we joined him after a team fight (that he wasn't in) he would stop tanking the baron when me and the other guy was at half hp when he was at full and was pretty tanky. We could win fights but he made it very difficult because we were out numbered. We almost ended the game multiple times. If we had a an extra member we could win the game because at the end of each fight 3 of their team members would be left at 0 hp ready to be cleaned up by lee but he would ignore us. He tried to base race 5 people on his own and we lost.

He can't be banned because he was playing the game but being in the match he trolled all 4 of us on his smurf. It's sad to see people play on smurfs because they are hardstuck in their rank and troll lower elo matches and not get banned. This is part of the reason why this game is in such a terrible state because trolls won't get banned.

He even tried adding me after the game. I added him back and he asked if I wanted to duo and I told him stop trolling matches then unadded him.