So you tried calling Booking support by phone and they didn't pick up? I ask because I personally had to call their support before a couple of times and they responded almost immediately. You do need to provide booking ID for that to happen though.

Contrast to Airbnb, which was so bad I deleted my account in.

Contrast to Agoda, which after charging my debit card required government ID scans within 2 hours-- or immediate cancellation & no refund. Stay next morning in foreign country, what if I was on the damn plane already? Never had an account with them and probably never will.