You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I help you today?

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

ASSISTANT: Sure, I am here to help you with that, can I know your good name to proceed further?

USER: Sure, myself Gary Clark.

ASSISTANT:  I am very sorry to inform you that there is no reservation found under your name in our database.

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

ASSISTANT: Thank you for reaching us.