Hi, I am wondering why haven't you called Airbnb to ask them about this? have you a Strict policy cancellation that allows you to get paid 50% of your guests pay out and they cancelled way too late to get their money back? Unfortunatley you are not providing enough information about this to help you as you listed no details about when guests cancelled but I highly suggest that you contact the Airbnb customer service for further explanation so you have a better understanding as to WHY they are taking a payment from your future bookings. But thanks for posting this concern.....just make sure you leave enough information so others can help you more. Good Luck
If you feel that me or another host have helped you, feel free to click on the "thumbs up" button at the end of any post. Thank you so much.
Aloha, Momi
Great way to contact Airbnb or via Twitter at AirbnbHelp / Facebook