Change Booking Dates

I've tried in vain to change my booking by emailing Booking.com but to no avail. My booking WAS for the 23 August 2019 (which I NEVER TOOK) for 1 night, 2 people. The mistake was because Booking.com website default to the day; I put in the CORRECT date to start of with but the Page altered the dates I intended to book for, which was the 20 September 2019. I've paid IN FULL so ALL that needs to be done is a CHANGE OF DATE. I've spoken to the Hotel and the receptionist said I have to contact Booking.com as they change the dates, NOT THE HOTEL. 2805.816.265 NR2 UK *Before I realised I had booked the wrong date AFTER 9PM on the 23 August 2019, I asked to check in at 14:00-15:00 which proves it was a erroneous booking.

PLEASE ASSIST Thank you