atreon keeping the money is illegal as hell, sorry for the language. They either must allow you to clean out what you need or take the risk of a law suit. 8k is a lot of money and if it gets into a law suit, and you win, they lose more. I never liked Patreon, the site is difficult to navigate, unless you have an account then everything is locked and requires card information to create an account whether it be a debit or credit card.
I'm honestly glad you got out of there, I have heard many devs getting screwed over by patreon and banned them, and more