I got banned for 2 weeks for the same thing, so I guess you're sorta lucky... sorta. Moral of the story: don't even talk. Riot can't police this game and people just use pregame to put you on tilt then ask the enemy team to report you afterwards. All it takes is one bad luck instance of that and you just got banned for being angry at being trolled or griefed. I've seen people posting logs of how they got punished for simply asking people to gank or play safe, and another instance of a guy getting punished when he didn't even say anything. It's mob rules on this game and the majority of players are raging jerks who will instantly devote as much time as it takes to grief you the second you do or say anything involving them.
If you talk to Riot about it, they will be unapologetic, they will never revert anything(not even your honors), and they will just leave the system broken and move on. They don't really care, and they never will until it actually starts damaging the player base, which is inevitable. If they want the game to be run by sociopathic spoiled children, than I guess they're moving in the right direction.