I feel for you, I really do. But the problem that arises here is that Riot cannot go back on their policies, especially not for some players and not others on grounds of those players having spent some amount of money on the game.
The price for disregarding the rules and punishments set in place enough times to incur a permanent ban is, well... a permanent ban. Riot does not care how much money anybody spends on an account, breaking the rules that badly incurs an indiscriminate punishment.
They won't encourage you to make a new account, but you technically can, and you're free to play on that one as long as you do not break the rules while using it as well. But you will not be seeing your old account ever again. That is how Riot deals with behavior such as the behavior you exhibited however many years ago when you first received a permanent ban on your account.