Unauthorized prepayment and refusal to refund

I booked this stay on December 29, 2019. An unexpected pre-payment for the total ammount of the stay immediately went off from my bank account followed by a letter from Booking.com confirming this. I found it strange, because it said on the listing the total ammount is only payable a week before your stay. The stay was only to be March 26-27 of 2020. However, because I’ve used Booking.com so many times in the past successfully, I trusted they would protect me. And when I canceled the booking on 20 January 2020, because the 12 guests involved couldn’t get leave for the specific dates, I expected a full refund, because on the listing it said free cancelation. After numerous e mails to Anandi Guesthouse via Booking.com the only response I got is: “I send your email through to my boss regarding the pre-payment. He will handle your request.please bare with us.” As on today, 2 February 2020, I have heard nothing back from them. My husband decided to phone the guesthouse directly, but they refused to give us a number for the ‘boss’. I will never recommen Booking.com to anyone ever. I am very disappointed in the lack of support from Booking.com.