banned my supports pick

Who was your support pick? Blitzcrank? If that was your only support pick, you should know better. Blitz is mind-numbingly easy to use and because of his grab, almost an instant ban.

You need to find a way to make them regret doing that. I typically take another high-powered (possibly support) champ and take CS/kills/everything. No player should ban something you've pre-selected. If they do, show 'em the ropes.

I usually pick someone who sucks for that role. Didn't like volibear? OK, I'm going to be zed. Hope you have tanky adc who doesn't want kills post 6