You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I assist you today?

USER: Can you please help me in changing my existing reservation, as my exam got postponed.

ASSISTANT: Sure, may I know your name to check for the previous reservation?

USER: Myself Barbara Wilson.

ASSISTANT: Please allow me a moment.

USER: Ok.

ASSISTANT: There is no reservation found under your name in our data base.

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for contacting us.