You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am John Anderson.

ASSISTANT: How can I assist you?

USER: I need to amend my reservation, can you help me out please?

ASSISTANT: Sure, I will help you to change your reservation.

USER: Thank you.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: That's ok, no problem. Thank you for your help.

ASSISTANT: Welcome, have a nice day.