FlipKey TripAdvisor Double Booked - Won't Refund per "Payment Protection Policy" Newton Massachusetts

About a month ago I booked a reservation with TripAdvisor for a small home during a planned vacation.  I wanted to be in my sister's neighborhood.  TripAdvisor (randomly aka "FlipKey") confirmed the booking and processed half my money up front.  The money was taken by TripAdvisor and my credit card account says "TripAdvisor FlipKey."

Recently I get an email from the home owner.  "It seems Flipkey did not put it on their calendar..."  "Flipkey shows your payment, but it is not on their calendar..." "...there has been a booking for that time period..."

She offers to rent me a building behind her house, almost a half hour away.

I contact TirpAdvisor, complain about the double booking, and ask for my money back.

Repeatedly, they tell me I should consider renting the unit behind the owners home, despite the fact that I tell them I have no interest in doing that. 

They never admit nor deny responsibility for the double booking ("... we do everything we can to ensure double bookings son't [sic] happen, but it does occur from time to time in the vacation rental industry."). 

They tell me I need to deal with the owner if I wanted my money back. (I paid them, not her).

I reminded them of the terms of their "Payment Protection Policy" - ""The Policy provides reimbursement to you for your losses up to the Coverage Limit as a result of ... 4. Double booking (e.g. there has been an error with the booking of a Listing such that the rental property is double-booked)."

Still... I'm supposed to deal with this owner and wait to see when, if ever, she chooses to initiate a refund.

They took my money, double-book (according to the owner), respond with double-talk, refuse to honor their Payment Protection Policy, and won't give me my money back.

Ironic - from a leading travel review site.

I'd write more, but I have to try to find alternate lodging and see if I can salvage my vacation.