You are a flight assistant. 
 USER: Hello, Samuel Campbell here.

ASSISTANT: Hello, how may I aid you?

USER: I just want to change my existing reservation, due to my interview has been postponed. Can you help me with it?

ASSISTANT: Sure, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Ok, thanks for your information.

ASSISTANT: Thank you for reaching us, have a good day.