So you get angry when teammates perform poorly yet fail to realize that you raging at them is only gonna make them perform worse. How would you like it if someone raged at you whenever you performed poorly? You say that you tried using a keybinder to block enter yet turned it off anyway when your teammates performed poorly: this is a problem with you and not your teammates. Have you tried just unbinding your Enter key from your keyboard or raging at the screen instead of in chat? These tools can only do so much on their own, but it's up to you to actually find other outlets to vent your anger in. Otherwise expect to continue to get permabanned for your inability/unwillingness to control your behavior.
P.S. Riot will never permamute you because that wouldn't stop you from griefing teammates in other ways that are not chat related.
P.S.S. It's natural to get frustrated when someone is performing poorly, but raging at them whenever it happens isn't gonna magically help them play better. Try saying stuff like "hey try hugging your turret a little bit more" instead of "stop messing up!". Teammates are more likely to listen and improve if you build them up instead of break them down.