Help with promos..

I get to Bronze 1 and then into promos, and then I get trolls.. I'm not exaggerating this.. The last time i was promos, I had a bard that said he was going to throw us the game because I said I was in promos. (I was even't rude... I was excited and supporting the team as support)... The bard proceeds to ult us everytime we went to engage a teamfight, letting the enemy team kill us D:... He even ulted Riven when she was about to steal the Baron.. The other time.. I just have teammates that try to 1vs5, so then I try to split push ( I mainly play sivir) and that doesn't succeed. I do want to say that 9/10 I win lane. I even won lane with the Bard that was trolling my last game.. How do you carry your advantage after winning lane as adc?.. I goto other lanes and try to push towers but my teammates just don't respond to my efforts and just do their own things.. I even have to remind them after we win teamfights to push our advantage by taking towers or any objectives (Almost every game).. Have I just been unlucky and just need to keep trudging through or is it because I'm just trash? :..