Ranked

I know you cant do anything about it but ive had 3 trolls in my last ranked games that makes it impossible for me to climb, take my last game for example. The bot support decides to stroll up mid and feed the enemy velkoz, he wasn't trying to gank mind you. He actually just auto'd the velkoz under tower. He did it 2 times then headed top and did the same. Meanwhile our bot lane was all alone, I know I'm not a diamond player but come on, how do you climb with trolls every game. Rant over.