submit a support ticket
This is 95% of all ranked queues.
One player already tilted or doesnt want to even try because of someone else's pick.
You submit a Support ticket or message them on Twitter.
If you do play the game out, mention their actions in the pre-game.
Submit the screenshot and submit a ticket to support. Someone did the same to me and they said it warranted and investigation and they would look into it. However, they cannot disclose if a punishment was issued or not. But better than nothing.