You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Scott Walker.

ASSISTANT: How may I assist you today?

USER: I need to change my existing reservation as my exams got postponed, Can you please help me with that?

ASSISTANT: Sure, I am glad to help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Sure.

ASSISTANT: We regret to inform you that, there is no reservation found on your name in our records.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for reaching us, have a great day.