Oh no Lee, this is not good!
something doesn't sit right here, if Airbnb cancelled your reservation, the guest should no longer be in your property, you need to contact Airbnb ASAP and speak to someone in person. Inform them that they have cancelled the reservation yet the guest remains in your property as such you require them to contact the guest ASAP and ask them to leave. In addition, ask for payment to be considered for the time the guest has remained in the property after the reservation was cancelled; I'm assuming you have asked them to leave, right?
It is one thing for the guest to complain, s/he has a right to do so and Airbnb will decide of their complaint is justified as well as any refunds due if the guest decides to cancel the reminder of their stay. However the guest no longer has the right to be in your property and should have actually left the premises as soon as the reservation was cancelled.
Also it makes no sense that a guest complains, requests to cancel the reservation due unacceptable conditions yet still wished to remain in the property; the conditions couldn't have been that bad, seems like a scam to stay cost free in your property.
Try this link to see if you can use one of the telephone numbers Contact Airbnb , Alternatively use Twitter or Facebook, provide brief details and request a contact number or a call back.
I hope this get sorted out quick,
Ama
