You can contact United Airlines via phone by calling +1-866-666-0225. This number is for English-speaking customers. Those speaking Cantonese can call 1-800-551-0943, from 8 am to 6 pm every day. Dutch speakers can contact 1-800-225-8612, from Monday to Friday, from 2 am to 10:30 am. Likewise, there is help for other languages also like German, Hebrew, Korean, German, Spanish, Portuguese, etc. You may visit their contact page for more details.