Booking.com complaint: Booking.com robbery

Booking.com allowed a booking to come through on Aug 11 for Aug 13-15, I immediately checked the calendar because I knew already that the month of August has been full. Lo and behold, those dates were booked and blocked on Airbnb since mid-July! I contacted the guest immediately to inform them of the issue and asked them to seek other accommodation; sent them a screenshot of Booking.com Calendar showing that the dates were blocked and his supposed reservation does not even show on it. Despite having done this an hour after the booking, the guest raised issue with Booking.com

Unbelievably, I received an email invoicing me for 104euros!!!! This is completely insane!! Is this the new business mode from Booking? Creating false reservations and steal from hosts?!!

I sent them emails and called customer services, all to no avail. I have not terminated my listing. I do not appreciated thievery!