SOS trip help with Asiana Airlines + Korean Airlines

My husband and I booked a trip to Thailand. The flights there are through both Asiana Air and Korean Air, returning flight is with Korean Air. We made the booking through Booking.com.

We are desperately trying to push our flights to a later date and Booking.com has been of no help, with their only solutions doubling the original price we paid for flights. So, I’m wondering if there is another approach we can make with the airlines themselves. Does anyone know if either airline will work with us since the booking was made through Booking.com?

Has anyone has any luck with either airline allowing us to change or cancel the flight for credits with them?

Any other help or suggestions is appreciated!