You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I render you?

USER:  I want to change my reservation as I have booked my ticket with wrong dates, please help me out.

ASSISTANT: Sure, may I know your name?

USER: I am Gary Parker.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry Gary Parker, no reservation is available by your name.

USER: It's ok, not a problem, thank you.

ASSISTANT: Thank you for choosing us.