You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Gregory Edwards.

ASSISTANT: How may I guide you?

USER: I want to change my existing reservation, can you help me for that?

ASSISTANT: Sure, I am here to help you. Please hold on a moment. Gregory, no reservation has been found on your name in our database.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.

USER: Welcome.