Booking is charging me for a cancellation

HI, had a guest book on-line, then cancelled, after I advised them not to, by explain gin the policy. 

Booking is now charging me the full rate, and refusing to continue payouts until this is cleared. 

My question is; if a guest cancels, a month in advance, why is Booking charging me? 

This is urgent because, with the COVID situation, I am extremely reliant on payouts. 

Thanks