i keep getting bad teams

how do i stop getting bad teams i cant do anything i get autofilled all the time and im sick of this only im doing good on my team and i cant carry cause they snowball enemy so hard or have 2 losing lanes and a trash jungler i got demoted at the end of the season and i can flame them cause i will get banned im so pissed every damn game there is 1 idiot who feeds and makes the game impossible to win