This phone number is listed on their official website. Simply call the number and follow the prompts to speak with a customer service representative. How do I speak to Singapore customer service? To reach Singapore customer service directly, you can use the toll-free number. This line is designated for quick connection with their support team.
Source: https://community.sfn.org/index.php?/topic/8656-1-8004759578how-to-get-a-full-refund-from-expedia/