https://forums.serebii.net/threads/8-effective-ways-to-reach-united-airlines-customer-service-by-phone-chat-and-email-an-explained-guide.773486/
https://official-expediatravelhub.elevio.help/articles/5-how-to-get-in-direct-contact-with-american-airlines-customer-service-via-phone-chat-and-email-the-complete-help-manual
https://community.fmca.com/topic/26166-step-by-step-guide-to-expedia-customer-service-via-email-chat-and-phone-trusted-official%E2%84%A2%EF%B8%8E-helpline/