You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Christopher Anderson.

ASSISTANT: My job is to assist you with your concern, may I know your concern?

USER: I would like to change my existing reservation. Will you help me with this?

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, there is no reservation been found on your name.

USER: Ok, not an issue. May be something went wrong while booking the ticket previously.

ASSISTANT: Thank you for choosing our agency.

USER: Anyways, thank you for providing information.