You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I want to change my existing reservation. Can you help me in that?

ASSISTANT: Sure, I am very happy to help you with that.

USER: Thank you.

ASSISTANT: May I know your good name please.

USER: Myself Raymond Allen.

ASSISTANT: Sorry, no reservation is found on your name in our database.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.