In other platforms it is possible to erase the review if the host can prove that the guest is blackmailing with a bad review in exchange of a refund.
Report any kind of abuse and document everything. Avoid conversations over the phone and have as much as possible stated on Airbnb's chat.
If you happen to find one of the rotten apples in the basket, take it as a loss and refund the guest. This is a long term business and losing some money is better than losing your status.
Customer Service will always stay on the guest's side. In order to change their mind, gather as much data as possible and share it with them.
They know you need them more than they need you. Bear that in mind and select your guests carefully.
In the past, when we have found guests like those we have left a reply to the review stating the facts and the guest's conduct, have rated the guest accordingly and marked him as an undesired guests for other hosts. That should be enough to avoid future abuses in the platform.
Best,
O&L.