PSA: If someone bans a champ you wanted to play...
Please, for the sake of everyone's sanity, just suck it up and pick someone else you're comfortable with playing in your role. No one one your team wants to lose LP dodging you, and no one on your team wants to sit through your 20-minute long feeding/AFK tantrum. If you really don't have any other champions you can play in the role you're given, then politely ask your team if anyone is willing to swap roles. It won't always work, but the worst thing you can do is ruin the fun of four other people just because things didn't go your way.