You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation due to postpone of my exams, can you help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name please to check your reservation status?

USER: My name is David Carter.

ASSISTANT: Please hold on a moment.

USER: Sure.

ASSISTANT: David Carter, no reservation has been found on your name in our records.

USER: No issues, thank you for the checking.

ASSISTANT: Thank you for reaching us.