You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Due to changes in my plans I need you to re-book my flight ticket. Please help me.

ASSISTANT: Sure, may I know your good name please?

USER: My name is Raymond Walker.

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

USER: That's ok. Thank you.

ASSISTANT: You are welcome.