So sorry to hear about your experience , but I agree with @Linda108
Why did you let the guests check in with 4 more people than had booked and why didn't you ask Airbnb to cancel the booking after they ignored your requests to quieten down.
Why did you wait until the guests had left to ask for extra fees, and then only ask them to cover two additional guests when there were four?
Personally in situations like this, I wouldn't let them check in and would refer to my house rules which prohibit additional guests.