@Andrew1962 No, the agent is not actively trying to hurt you. Airbnb is guest-centric and almost always panders to the guest at the expense of the host.
A guest who contacts Airbnb with complaints, rather than first contact the host is pretty much always a scammer looking for a free stay. It isn't a matter of them being unhappy with their stay- they want to stay for free.
Of course, if the host isn't responsive to legitimate complaints or questions, then the guest's next step is to contact Airbnb.
You did nothing wrong in the way you handled this. You need to find out if this was registered as a host cancellation, and if so, fight that.
But there are "neutral" cancellations, done by Airbnb which penalize neither host nor guest, so hopefully it was registered as such. Can you see whether you have a cancellation in your stats? That would indicate that they penalized you. If you don't see that, it was a "neutral" cancellation.