You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: I want to change an existing reservation due to sudden change in my trip.

ASSISTANT: Sure, may I know your good name please?

USER: I am Emma Smith.

ASSISTANT: Ok, please wait a minute.

USER: Ok.

ASSISTANT: Thank you for your time. Unfortunately there is no reservation found by your name.

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

ASSISTANT: Thank you for opting us.