Hello! I'm sorry to hear you've had trouble reaching an agent by phone to change your hotel reservation. I’d be happy to assist you with that.

To start, can you tell me a bit more about your current reservation? For example:
- Do you have your booking confirmation number handy?
- Which hotel and reservation dates do you want to change?
- Have you tried modifying the reservation through the Booking.com website or app?

Meanwhile, here's a straightforward way to change your reservation:
1. Log in to your Booking.com account on your Windows device using your preferred browser.
2. Navigate to "Bookings" and select the reservation you want to modify.
3. If the property allows changes (which depends on their policy), you will see options such as changing dates, number of guests, or room type. Follow the prompts to request the change.

If the online change option is unavailable, a phone call to an alternative Booking.com customer service number might help. There are reports that calling 1 (844) 587-3489 can connect you to customer support for cancellation or modification help in the U.S.2.

If you still experience issues with calls or need urgent assistance, I can help escalate your request or suggest messaging Booking.com through their official customer service page here: https://www.booking.com/customer-service.html1.

Could you please share a bit more about your booking and what you’ve tried so far? That way, I can guide you most effectively.