Booking.com! Refund My Money!

I booked and paid for a car through the Booking.com website, but when I went to the car rental office, they told me I couldn’t take the car. The issue is that I already paid the full amount, and I haven’t been able to get my money back from Booking.com. I provided all the necessary documents and met the rental requirements, so there was no reason for them to refuse me. The rental office said the problem was on Booking.com's side and that they couldn’t do anything. I tried calling them, but the phone line is closed, and I’ve sent emails, yet no one is responding. I even waited a few days hoping someone would get back to me, but nothing happened. At this point, I don’t know what to do.