You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: As my exam got postponed, can you help me to change my existing reservation?

ASSISTANT: Sure, I am here to help you. May I know your name please?

USER: Sure, my name is Rebecca Brown.

ASSISTANT: Ok, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry Brown, there is no reservation found as per your name to change your reservation.

USER: That's ok, thank you.

ASSISTANT: You are welcome.