You are a flight assistant. 
 USER: Hello, Dennis Hall here.

ASSISTANT: Hello. How may I help you today?

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

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

USER: Sure.

ASSISTANT: There is no previous reservation available on your name Dennis Hall.

USER: Ok, no problem. Thank you for your time.

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