You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hi, how can I help you?

USER: As I am having some emergency work, I need to change my existing reservation. Can you help me with that?

ASSISTANT: Sure,. May I know your name?

USER: My name is Stephen Davis.

ASSISTANT: OK, please wait a minute.

USER: OK.

ASSISTANT: Thanks for waiting. We find no reservation that matches with your details.

USER: Thanks for the information.

ASSISTANT: Thank you for contacting us.