You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name please?

USER: I am Frank Jackson.

ASSISTANT: yes, how can I help you?

USER: My exams have postponed, so I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found by your name. Do you want to have any more information please?

USER: That's ok. Thank you for your time.

ASSISTANT: Thank you and have a nice day.