@Stephanie792,
I am glad to hear that things worked out in your favor. What did you ask Airbnb to assist you with, and they declined? I think that the only thing that they could have done is cancel the reservation if you'd requested due to the additional guests. If you didn't call, and request a cancellation when you found out about the additional guests, and let the guests stay, then Airbnb would not try to acquire payment of fees after the completion of a reservation. They usually do not charge a guest for breaching house rules, only for damages or if excess cleaning is required.