You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Due to some issues, I am planning to change my existing reservation. Can you please help me for this?

ASSISTANT: Sure, may I know your name?

USER: Myself Gary Hall.

ASSISTANT: Sorry, no reservation found on your name.

USER: Not a big problem, anyway thank you very much for your service.

ASSISTANT: Thank you.