new queue

So i was just wondering where in the report section after the game that you report someone for playing a role after someone else has already queued and got the role?? example is i was playing a ranked game yesterday. The other team had a jungle Twitch and a jungle Nunu, leaving the other lanes to solo... after asking the other players they say nunu was the one who was given the support role... and all he did was follow twitch around the jungle taking the camps with with consume and smite.. so like i asked above.. where does this fall under for the appropriate section to report them under and does riot punish these people any stronger then other offenses??