Issue with Player in Matchmaking Ongoing for Weeks

Dear Moderators and 343 Team,

I am not going to name this individuals gamer tag on Waypoint but I’m hoping someone can provide me information on how I can report abuse in Matchmaking.

Despite blocking this player on Xbox 1, I’ve been paid with this individual 3 times over the course of the last month and had him play against me today (his whole team quit on him so I wasted my 15 minutes of my life on this).

This one individual is single handedly ruining Team Slayer for Halo 5. He does just enough damage to you not to kill you right when he knows you will face enemies. If you still almost win, he start betraying himself. He also will clean up and enemies kill, so if I kill someone and have low shield he will come and kill me…all this is done when he is on your team.

This has gone beyond deranging, it seems to me this guy actually just gets onto Matchmaking to ruin other peoples lives.

I know many people who have reported him and I always message people to report him when he ruins a game I’m in. What else can I do?