You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you/.

USER: I want to change my existing reservation, due to some personal problem. Can you help me?

ASSISTANT: Sure, I am here to help you for this. May I know your name please?

USER: Thank you. I am Stephen Hill.

ASSISTANT: Just a moment, let me check your reservation status in our database.

USER: Sure.

ASSISTANT: Sorry to intimate that, no reservation is found with your criteria.

USER: Ok, not an issue.

ASSISTANT: Thank you very much for connecting with us.

USER: Thank you for your information.

ASSISTANT: You are most welcome.