You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me in changing my existing reservation, as my exam got postponed.

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Myself, Frank Johnson.

ASSISTANT: Sorry to inform you that there is no active reservation on your given name.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for contacting us.