AirBNB Cancellation Penalty - unfair ruling

[Ian61]

AirBNB recently docked me $125 for as a cancellation fee for one of my guests cancelling, due to a legitimate communication error, but before the  check-in time (i.e. patience would have allowed the issue to be resolved). 

Additionally, I could not re-list my place and therefore lost potential revenue. All told, this cost me several hundred dollars. 

AirBNB contacted me but did not seem to pay any attention to my explanation. 

Where/who can I take this up with?

It's totally unacceptable.