What to do against "Best Duo Bot NA"?!

I get this almost every other game. Some randoms bragging about how they are the "Best Duo Bot" and how noone can match their "Sick Pro Skillz". Well, I just about had it. You can guarantee that they are going to feed and you know that they are going to blame their team. I don't want to dodge because I don't want the penalty, but I don't really see any other option.

I'm not going to name any names, but last game, I had two people get into the chat, instalock, and type "Best Duo Bot", "Duo or Feed". Well, the game started, and within the first 5 minutes they had already lost their tower and were 0/2 and 0/3. At the end of the game, their scores collectively were 2/18. How is this even allowed!! How can I not get these trolls? The worst part about it, was when the adc was at 0/7, I said "Ok, you need to pull together and ward your lane and stop feeding the enemy adc." Well, apparently, that didn't sit too well with them so at the end of the game both spammed, "Report X______ for Verbal Abuse"!! I received 3 reports right them because I just told them not to feed and get their lane together.

I need a Rioter to explain why an option to kick trolls in champ select hasn't been implemented yet. They completely ruined the game for everyone else. Even the enemy was like, "wow, your bot sucked". To which they replied "It was our TEAM" "THEY DIDNT HELP US!".

So, how do we get rid of these people?