You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

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

ASSISTANT: Sure, may I know your name please?

USER: I am Justin Martinez.

ASSISTANT: Justin, there is no reservation with your name to change further.

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

ASSISTANT: Thank you for reaching us.