You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Can you please help me out in changing my existing reservation?

ASSISTANT: Sure, may I know your name?

USER: Sure, my name is Dennis Miller.

ASSISTANT: Sorry, there is no active reservation on your name. Thank you.

USER:   Ok, no problem. Thank you for the response.

ASSISTANT: Thank you.