Please Forgive This Loss

So I was playing a ranked game, all in fun I want to try and climb, I get into lobby pick Jinx get right runes masteries and spells and i afk until game starts. I get into game, i have a GP Support, im thinking alright this guy is up to something lets give him a chance. He runs into the enemy AD and Supp and instantly gets blown up. I ask him if hes trolling and he says no hes just bad and I leave him alone. This obviously continues and later on when we are getting rolfstomped I say I think that GP is a troll. He's the first person to reply 'I am trolling'. Later I say maybe he isn't trolling and GP is just a very bad support to play, he says 'I told you I am trolling'. I mean if someone in a game admits they are a troll and trolls is that not enough to give me back my 19 lp? and 30 minutes?