You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello,.

USER: I am Gregory Campbell.

ASSISTANT: What kind of service are you expecting from us?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I can help you in that.

USER: Thank you.

ASSISTANT: Please wait, let me check your reservation status.

USER: Sure.

ASSISTANT: Sorry George, there is no active reservation found on your name to change it.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thanks for choosing us.