If you get banned for 14 days Riot help

I just got banned for 14 days and i wasn't toxic for 1 month and was reformed but last night i had one bad game and was toxic but wasn't that bad and say now since my 14 day ban if i were to be toxic for ONE game i'm permanent banned how can i avoid being permanent banned cause everyone can be toxic one game out of 1 month and your going to ban them which is really stupid i think if your reformed you should go back down to 10 game restriction but how long would it take to go back down so i wont be perma banned i have learned my lesson and i will try not to be toxic anymore but i want to make sure i wont be perma banned cause i put to much money and time in this account to only be warned 4 times which the warnings aren't a lot Please tell me how i can avoid being perma banned after 14 day banned because if i were to be toxic one game cause of a player i would be perma banned which really isn't fair if possible