Who would I need to speak to in order to report a booster?

I need someone to help me find a way to report a booster, in the last two games I've played, I've had one of the same players in my game both times, also both times he has played Talon and wrecked on whichever team he was on..... Now normally I would not take note of that, maybe he is just a very talented Talon main, however, in both postgame chats he has made one comment, and one only "Are you feeling stuck in a division where you dont belong? I can help with that! Just add me for details!" This strikes me as very "account booster-ish" type behavior..... I would really just like someone who has the ability to do so to look into this for me, please. It kind of ruins the game when you're playing with someone who is obviously alot more skilled than you are and is obviously not playing at their skill bracket intentionally. Thank you for whomever's time I take up in researching this matter, and if anyone has any further advice on how to get this issue looked into please feel free to tell me.