You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I do for you today?

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

ASSISTANT: Sure, may I know your good name please?

USER: I am Rachel Carter.

ASSISTANT: Ok, please wait, let me check with your existing reservation status.

USER: Sure.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: No problem, thank you for the checking.

ASSISTANT: Thank you for reaching us.