Nearly 5 months of good behavior, yet permanently banned.

I have invested over 800 dollars on this account. And I love League of Legends more than any other game on the market. I am not a perfect human being, and sometimes I say things which I later regret. It has been a long time since the last time I got in trouble for my behavior (Almost 5 months clean). However today, I was a bit toxic in a few of my games because I had a bad day, I received a permanent suspension, but was also puzzled because I thought that I climbed back in the ban pyramid a long time ago due to my positive behavior. I didn’t think that a permanent suspension would happen. I was even able to receive keys and hextech chests up until a week ago. Which technically means that I have been reformed, no? So do you not think that a permanent ban is a bit too harsh for someone who showed improvement for nearly 5 months, just because of single fallout? So much for the 3 month rule.