@Cory102 The way a host can request extra money [using the Resolution Center] also requires that you ACCEPT the extra amount. AirBNB doesn't ever charge a credit card without authorization from the guest, so something odd is going on here. [As a host, there are times when I wish they did.]
If I were you, I would simply contest the charge with your credit card company, but there is still a mystery that I might wish to solve. The question becomes, how much time do you wish to invest in learning more.
One more thought.... is there any way that this is your second installment to pay for the original reservation?