You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I serve you at this moment?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, may I know your good name please?

USER: I am Christopher Taylor.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: Ok, not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you for the information.