Please Fix Matchmaking

From the title, you might be thinking 'what does he mean?' I will tell you what I mean!

What I mean by fix matchmaking, is that I was recently demoted for the third time in 2 weeks. Two WEEKS! Please tell me how that makes any sense, whatsoever! I mean, do something! Because I'm tired of grinding into S3, winning maybe two games, and then I go on a losing streak back into S2. Anything I do doesn't seem to matter in game! I can be jungle, set my top and mid ahead, lose because bot ADC is fed. Win top. They're jungle and mid get ahead. I lose. Bot lane. We're 4/1 as a whole. They're ENTIRE team comes! LOSE! SOMEBODY, PLEASE DO SOMETHING! It's to the point, I'm starting to not even want to play anymore. And I've been playing since 2010. I have a good understanding of the game. I can do skirmishes and brawls fine. But when it comes to teams, mine always seems to be not quite as good. So I'm just hoping maybe there's some kind of system you could come up with to level the playing field. Because I'm tired of losing to stupid stuff. End rant.