PSA: Punishment tiers don't have a set date for descending them, much like hextech eligibility.
I still see people saying that it's 3 months to drop a tier, but that isn't how it works. Rioter response I received when asking about my own bans:
AGENT SPOOPY - April 07, 2016 14:16
Hey again,
That is something I can definitely help you out with! I'll outline all the steps your account went through below:
10 game chat restriction, October 24th 25 game chat restriction, November 3rd 2 week suspension, November 7th to 21st Permanent suspension, February 5th
I've heard this 3 months guess thrown around by a lot of players, and I'm not sure where it came from, but that's not quite how it works. Depending on the level you're at, the amount of time it takes to decay changes significantly. Higher tiers require a longer amount of time and more games played for the status to be adjusted. This is just an example so don't take it as an accurate representation, but a 10 game chat restriction could take only a week or 2 to wear off, while a 2 week suspension could take several months since it's the harshest punishment there is (prior to a permanent ban anyways).
Additionally, the amount of time it takes can be shortened or extended depending on the player's behavior. If a player has 10 games with good behavior for example, and then has 1 game of bad behavior, this could revert the progress made by those other games and keep the player's account in a state of negativity limbo.
While it is possible for an account to skip tiers and just jump to a permanent suspension, your account was escalate from a 2 week to a permanent one in this case.
Hope this helps to clear everything up for you. :)
Agent Spoopy Player Behavior & Game Support Candy Collector ᕕ( ᐛ )ᕗ
Someone needs to compile an organized list of myths regarding the punishment system and the right answers to all of them so we can sticky it.