MONEY DEDUCTED AND ACCOMMODATION NOT AVAILABLE

I wanted to book accommodation via Trip Advisor. I had to give details of a card for payment with the enquiry. The money for the 4 days accommodation was deducted from my account. Unfortunately the accommodation was unavailable for the time we required but to date no refund has been forthcoming from Trip Advisor. I contacted the owners of the property and they did not receive an amount for this booking. I mailed Trip Advisor but no refund was forthcoming. My latest mail has been ignored. Where to now as the email address is all I can find to make contact with them!