I don't know how could it happen but somehow there is a double booking for the same period on my property. One on Airbnb and another one on bookingdotcom. As the airbnb was earlier and when I confirmed that one I immediately removed availability on bookingdotcom I think there is a software issue.
Anyhow: please tell me how can I solve this difficult situation. 10 minutes after he booking happened I already called support to cancel the reservation and I also messaged the guest that this reservation has to be cancelled
Thanks, for your help