Detailed information about sending money abroad is available at travel.state.gov
Bank transfers, temporary credit limit increases on credit cards, and money transfer services are all available in Cambodia. Then most up-to-date information about the physical location of Western Union branches in Cambodia is available on their website
If none of these options are viable, please contact us. The U.S. Department of State may be able to help transfer funds to a destitute U.S citizen overseas through our office in Washington, D.C. to the embassy.