Matchmaking Trolls

Riot Games I have been playing this game since season 3 and when I got to Eune in Season 6 I loved the game I wanst really the best but I was having fun. Today Im trying to go to Gold but it is impossible because of trolls in Silver, I got placed into Iron 3 this season and It wasnt hard to get out of bronze and Iron, but now that I am in Silver It is impossible to get out of Silver 3 I got to Promo games and Lost them, Nothing that I could do about promos teammates toxic so it is ok. But I got extremely titled when I got 2 afk teammates and 1 troll was on my team ofcourse I couldn't win that and another reason I cannot Climb is because I get only about 18-19 LP. I do not understand this because I get good gradings and I do not understand how my MMR can be lower than it used to be, I litteraly Get S- or S sometimes A+ A so on so forth... My lowest grade is C+ this last game when I had 2 afk and one troll so please explain why is my mmr down. Jinx was trolling, Braum afk and Kayn afk. Braum went afk on purphose when he died for the first time, same for kayn.