Cant win any games

Its a real struggle for me to get over 800 elo. Im losing every game though im global in matchmaking. i have a k/d ratio of 1.5 but thats still enought. I dont know if its because i solo queue ane get toxic teammates all the time. But i win 3 games get 50 points. Then i get 3 loses and i lose 100 points. I thinnk its a weird system, when i get 25+ kills every match