You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how may I assist you?

USER: Please change an existing reservation by name Daniel Anderson.

ASSISTANT: Sure, Please wait a minute. Let me check the availability of reservation with your name and get you back. Thank you for waiting, Unfortunately, there is no reservation found with your name to change it.

USER: Thanks for the assistance.

ASSISTANT: Thank you for approaching us, Have a nice day.