Unfair treatment for confirmation number *** pin 4647

I made a booking with booking.com on the 25 September 2019 for an accommodation in Durban called the white house b&b. After making a booking the said I must confirm with the accomodation if the received my booking . I called the white house and the lady on the other hand asked for my name and I have it to her, the soon as she heard my name and surname she immediately said the accomodation was full and I let it be and made another booking else where. The next day the sum of 3900 was debited from my account. I called the white house and the lady I spoke to this time said there's nothing they can do the money was deducted by booking.com . I sent an email to *** and explained what happened and they asked for all kinds off receipts from my current bookings and I have them everything they needed to this day I haven't received anything kind of refund from them.