You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Christine Jones here.

ASSISTANT: How can I assist you at this moment?

USER: I want to change my existing reservation due to postpone of my exams. Can you help me in that?

ASSISTANT: Sure, I will assist you with that. Please wait a moment, I will check your previous reservation status.

USER: Sure, take your own time.

ASSISTANT: There is no previous reservation available under your name.

USER: Ok, not an issue. Thank you for giving information.

ASSISTANT: Thank you for contacting us, have a nice day.