I was flying home from Indonesia, but because I lost some things (like ID) I could not make my flight. As their local booking office was not open on Sunday, I rebooked a one-way on a later flight.

As I did not fly the outbound part of my intinerary and could not rebook through them, can and how do I get a refund or voucher for future travel on SQ?

I am currently in China, but my ticket was issued via Amex Travel Expedia, so that would usually mean in the US. Do I contact the China office or the US office?

Thanks!