How to report post-game chat ?

I got the situation where during the game everything was pretty fine but after the game one dude was constantly harassing with death wishes. Does system reads post game chat too or flamers like that remains unpunished ?

I tried to report with included screen shots through ticket support but the answer i got from moderators was this:

"Hello verysalt,

Indeed, very unpleasant. :(

Thank you for this report! We can’t often take action on reports sent to us through tickets, but we created the Instant Feedback System to help us track when a player is consistently hurting others."