Poor customer service

I have been sent from pillar to post regarding a booking I made on Booking.com. I have been trying to change dates for my booking for the past month on the app and it won't allow me. It says I cannot make a booking a for a date over a year in advance. So when I contacted their customer service they said they would contact the property directly to have the dates changed but I'm still waiting and it's been over 2 weeks now. When I contact the property directly they refer me back to booking.com. My booking is for the 3 to 6 Jan 2021 and I would like to change it to 3 to 6 Jan 2022 as this is the only date I have available. I am now going to lose my money because of lack of service.