It's sad. I've already said this once in another thread. But it bears repeating here as well. Being permanently banned is a final straw. There are several warnings that you must go through before this final judgment is rendered upon you. You get warnings, increasing chat restrictions, and suspensions. All tell you that you are not behaving as you should. Yet people only seem to realize that it's time to modify their behavior AFTER they are permanently removed. To quote George Jetson: "Yer a little late, aren't ya, buster?" < insert Astro laugh here >
If Riot has already told you the ban was deserved, you've lost. Begging for a second chance after that is to no avail. You WERE given a second chance. And a third. And a fourth! Now, you're gone. I don't have a lot of sympathy for people in situations like this.
Make another account. But this time, keep in mind what will happen to you if you continue to break the rules. I would also caution you that if Riot discovers you're a player who has already been banned once, Riot may decide you don't need further warnings and outright ban your new account as well. They can do that.