Boosting Account Found

here:

https://support.riotgames.com/hc/en-us/requests/new

Make sure to select “I have a question About League of Legends/Riot Games” and category “Games and Features > General Questions”.

it helps if you have a screenshot to submit with your ticket.

I don't think he will get a punishment, i reported few players on previous seasons with obvious proof and players confess about be boosted, and riot didn't ban them, they still got border and other shit, and of course riot will say to you 'we can't give you the the outcome of the case sorry'

Won't make a difference more than likely. From what I have seen boosters and smurfs are let run rampant.