Hi, yes same thing happened to me when he called to confirm his arrival. I sent change of reservation to accommodate the new number of guests 9X since my listing is big.
Then guest refused the change with new price after the 4th guest .
I chatted "you refused to pay new booking while you're booking for only 4X" he said yes cancel the booking.
I cancelled and had the review and blocked calendar and after the third day I emailed Airbnb and explained all. Second day they sent me price of 2nights and waive the review.
Thanks Airbnb