No reply to repeated e-mail to be refunded for a cancelled booking!

On 13/03/2020 we booked 3 nights Accommodation in Sutherland through Booking.com because of an upcoming Conference. The Conference was cancelled the next day due to Covid-19, and so we cancelled our booking with the Guest House. Our fatal mistake was that we did not cancel directly with Booking.com. After repeated inquiries and communication with the Guest House over the next 5 months, it was established that they (The Guest House) never received money for this Booking and had contacted Booking.com to please refund us. After forwarding the names and e-mail addresses of Booking.com staff they had communicated with, to us, we did the same - asked for the money to be deposited back into our credit card, or deposit the money into our bank account. Not even a response (although I can see that they read it). Six months later - still waiting. Disgusting! The money does not belong to Booking.com, and yet they ignore us with impunity!