An update: I didn't have much time from the time I had posted to file for a dispute (a few days). I tried to see if I could have postponed the filing deadline with no avail so I filed a credit card dispute. The first bank representative was certain I had a more than valid case. The process as a whole was very opaque. In the end, it was deemed that there was no "billing error," whatever that means. I still believe my situation is valid and I'd like to find another means to resolve my discrepancy with AirBnB and receive a proper refund. What more could I do?