Consumer Complaint

Hello Peter, I like to lay a complain about booking.com, early this month I book an accommodation with them for La Mercy Beach Hotel on the 4th of August I paid full amount. When I arrived at the hotel they said I didn't pay so I have to pay again. Then I contacted booking.com enquire them about the issue they ask me to send proof and they will get back to me within 24 hours. Up until today they didn't and no refund. I'm very disappointed to them.