Toxic Player, couldn't report

I had this player just a couple minutes ago, whose name I'm not gonna write down since I'm not an asshole, unlike others. By the way, I started in chat with "mid or afk", and those 2 premades just started flaming me out of the blue. I'm a mellow kind of guy, and people usually don't get my jokes, so I picked my support, typing "it's fine, imma support" (it was a normal blind-pick and I wanted to play Zoe, so I went with that). Someone DC'd, so we had to get to another lobby. I found those 2 guys again and I typed "I said mid or afk". At this point they knew I was joking, but his premade friend stole my champion, which led me to play Diana jungle. Fine. I went to my blue, and this kid steals my blue with Nunu's Q. He's like "sorry, I missclicked". Well, no shit. I went mid to get my level 2, since his premade was there (he came mid too, but to troll), then went back to jungle. He fed first blood, and then proceeded to follow me and steal my red and my crugs (my smite damage was way below his Q) while I was there. After 10 minutes of agony, I said "I'm jungling now, can't we get over this?" and he kept spamming in all chat "report Diana for trolling and flame". He pinged me after every death. He danced over my champ dead body. He kept dying inside the enemy team for no reason, all while typing "report diana for troll". He kept the attitude for the whole game, stating that he always missclicked when he stole buffs, and asked others to report me for my "missbehaviour". League went on maintainance after the game, so I couldn't report him. Is there ANY way I can have this filth get what he deserves? I've played a lot of games (probably around 6k?), but I've never been so offended by someone in a game (after all, it made me write this post). Help, please.