Can't comment on an admin fee being a SC stat law - ask for written verification from the agent on that.
As for having additional commission brought up after the deal is struck, that does not seem right to me. I would be inclined to push back on that if you were not asked to sign something earlier that made this clear. Remember that a relationship is at the broker level so if you need to speak to the broker/manager to get clarity, do so. And do not sign anything until you understand what you are signing and are comfortable with it.
....just my opinion....
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