You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I just want to change my existing reservation, because of sudden change of trip.

ASSISTANT: Sure, can I know your name?

USER: Myself Carolyn Miller here.

ASSISTANT: Ok. Sorry to inform you that there is no reservation found on your name.

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

ASSISTANT: You are welcome.