You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I get off to you?

USER: Due to sudden change in the dates of submitting my research documents, so I need to change my schedule dates.

ASSISTANT: Sure, may I know your name to check the data base and get back to you? Ok, please wait for a while.

USER: I am Christopher Lee. Ok.

ASSISTANT: Thanks for waiting, there is no reservation found by your name in the reservation list.

USER: Ok, no problem. Thanks for your help.

ASSISTANT: Thank you for approaching us.