You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER:  Actually, I want to meet my friend in New York for that I reserved my ticket before one month back, but suddenly I had a another work at that time. So can you help me to change my reservation?

ASSISTANT: Sure, I will help you with the change of flight reservation. May I know your name please?

USER: Previously I reserved with the name of John Smith.

ASSISTANT: I regret to inform you that, there is no reservation on your name. Thanks for approaching us.

USER: It's not a problem.Thanks for your help and great service.