You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: As my exam got postponed, I want to change my existing reservation. Can you help me out?

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

USER: Sure, my name is Christopher Young.

ASSISTANT: Please allow me a moment.

USER: Ok.

ASSISTANT: Christopher, there is no reservation found under your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for contacting us.