Booking.com reservations

Did a booing on line but did not receive a confirmation of this booking. I have since call the Hotel in Athens, Wyndham Grand Athens For the 27/08/2020 to 28/08/2020, which has confirmed this booking with Ref no 2859.207.375 but could not give me a pin no. An amount of R3,052.01 ( EURO 84.00) has been deducted from my Credit Card on the 29/01/2020..This booking has been duplicated an need to have it cancelled. Unfortunately I am not able to communicate with booking.com as I require a pin code which I don’t have. Please can you assist Kind regards Jennifer Fawkes