You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Sarah Miller, here. Due to sudden change in trip, I want to change my reservation.

ASSISTANT: Ok. wait a minute Sarah.

USER: Sure.

ASSISTANT: Sorry Sarah, there is no reservation with your name.

USER: That's ok, thanks for your information.

ASSISTANT: It's my duty, thank you to visit here.