United Airline main customer service number is 1-800-United Airline or 1-888-447-6313 [US-United Airline] or 1-888-447-6313 [UK-United Airline] OTA (Live Person), available 24/7. https://clusterbusters.org/forums/topic/23536-six-ways-to-contact-how-do-i-speak-to-a-live-agent-at-united-airline/