The game I just had

Ok man, really tired of this kind of shit, I was 12/1 as lucian, pretty much already knowing i was going to win my second game in my promos to get into silver. Then I walk by our red and casually take it because, as im the most fed and the highest chance of carrying, why not take the red so i can peel for myself??? Then when I take it naut instantly begins trolling because I stole his red. I apologized but he wouldnt give up and eventually just stood at fountain, then when the whole team threatened to report he just walks around farming camps without helping to take drags/towers/anything. so from winning the game, we got destroyed because it became a 4v5. I never post on here but I just needed to vent. But what am i supposed to do in this situation?? We all report and he's still not going to get banned.