I have been banned for intentionally feeding, while I never do it. Here is the example case I got: http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/2540895914/27359788?tab=overview . As you can see, 90% of my deaths were under my own tower, as I got camped by enemy lee sin and support. They just abused Jhin's weak early game and I couldn't predict them to dive me. Lee Sin level 2 ganked me on top of that.
Here is the rest of my match history: http://matchhistory.euw.leagueoflegends.com/en/#match-history/EUW1/27359788 . I haven't intentionally fed in a single game and I got punished. Riot can check EVERY SINGLE one of my replays, I haven't intentionally fed ever. It would be impossible to try to feed enemy intentionally and still deal most damage to champions in every game almost. Common sense says that.
My suggestion would be for you to at least check where people died, to make sure they don't get banned for having bad games. In most of my games I am playing aggressively, but I'm not running into enemies to die on purpose.
Support refuses to help me, because they think that I have been intentionally feeding, and just give me the automatic response.
EDIT: Replay of the example game: http://www.twitch.tv /nigelfi/v/51688737 . Pay attention to Lee Sin level 2 gank, Janna 24/7 roaming mid, mid lane pinked from everywhere. (Link doesn't work very well so just combine the 2 parts of it)