Guest request free cancellation due to covid-19

Hi there, a guest has just asked to cancel his reservation with a full refund because of the covid-19 issue. I have said that I accept his request but see that booking.com will still charge a commission fee. I was hoping that no fee at all would be charged to either myself or the guest because of these extenuating circumstances.

The information that was provided on booking.com website was to contact booking.com and let them know about this so they can waive the fees. However it is very very very difficult to find a contact for any booking.com team member. Does anyone know how to contact them so I can get them to waive the fees?