When the ban is due to RIOT GAMES policies and the ABILITY to chat in game to begin with ... that is THEIR FAULT.
I suggest a CLASS ACTION LAWSUIT ... I too have an account that I invested HEAVILY into for my son (Nearly all champions and a ton of Skins) and he got banned also because of CHAT TOXICITY.
THE GAME causes people to become toxic, PEOPLE cause other people to become Toxic, RIOT provides the means for BOTH to thrive ... but when player toxicity ensues, they ban the toxic player. For games where money is involved ... this is THEFT ... you SELL ME SOMETHING I CAN USE but you TAKE IT AWAY ... that is stealing my property no matter how you look at it.
CHAT toxicity should always end in CHAT BANS ...
GAME PLAY toxicity should always end in "Time Limited" GAME BANS ...
Permanent bans WILL end in LAW SUITS ... that's theft of property.
Perma CHAT ban is a better option ... that will eliminate the "Chat Toxicity" issue 100% ... but may create a communication problem ... which could also be solved by evolving the standard EMOTE mechanism for in game direction ... this way you remove toxic conversation from the mix.
This game was created by RIOT ... the "game play" policies were created by RIOT ... the chat mechanism was created by RIOT ... the BAN policies were created by RIOT.
I am a consumer ... if this is how I am to be treated then I will never play Riot games anything ever again ... and disable all 3 of my accounts.