You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

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

ASSISTANT: Sure, I am here to help you. May I know your name to check with existing reservation?

USER: Myself Andrew Campbell.

ASSISTANT: I am sorry to say you that there is no reservation found under your name in our database.

USER: Ok, not an issue. Thank you for checking.

ASSISTANT: Thank you for opting us.