Matchmaking in this game

Is abysmal. This season I have climbed from bronze 5 to plat 5 playing the same champions and strategies. I made it to my plat 4 promos a few days ago, and since then the matchmaking system simply will not let me win games. It is absurd. I have changed absolutely nothing, but i just keep losing and losing and losing for no good reason other than matchmaking seems to want me to. I swear, there is a way for riot to flag your account if they do not like you and put you into a "loser" queue much like the lower priority queue system.