Booking.com taken money for accommodation not utilised.

I made a booking on Booking.com prior to the Covid pandemic in 2020 and paid in full for accommodation in Cape Town. We were not able to utilise the accommodation due to the lock down. After numerous attempts to contact Booking.com via their website and telephonically, I have not been able to get any further as their system states that the booking reference number they issued me is not valid! I have given up and am out of pocket for a lot of money. This is totally unacceptable and unprofessional for a large multinational.