toxic 4 man premades

So i know i am not the only one that has had to deal with 4 man premades. Normally i dont have a problem untill they start turning racist, homophobic, and flat out toxic in champ select. well today i got stuck with such a group and in game i did what i always would do in said situation mute and kindly ask other team to report after. well they clearly continued the hate speech in game because shortly after enemy players started asking them to stop talking like that or get reported untill they turned toxic as well out of frustration. now this isnt the first time a have had a game like this but i do feel that Riot needs a back out button in champ select that leave you able to report why you left and would show chat for champselect because i have seen the toxic verbal abuses in champ select that then dont say anything in game after saying things like " stfu %%%%%%" and "your just a %%%got playing that champ" or " fuck you %%%got i am going top because i picked said champ even after being assigned said role". some players cant put up with that kind of verbal abuse long so they leave games and get punished all because they didnt want to deal with the toxic players teaming up on them. now i am not innocent here i can be toxic at times like every other player BUT i go out of my way to say sorry before it gets to far