You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Mary Harris.

ASSISTANT: How can I assist you?

USER: I am planning to change an existing reservation, due to some work. Can you please change my reservation?

ASSISTANT: Ok, sure. May I know your name? Sorry, I did not fine any reservation on your name to change.

USER: That's fine. Thank you for your service.

ASSISTANT: Thank you for reaching us.