You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I serve you?

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

ASSISTANT: May I know your good name?

USER: Myself, Frank hall.

ASSISTANT: Sorry Frank, there was no reservation found on your given name.

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for opting us.