You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you now?

USER: I want to change my reservation, can you help me?

ASSISTANT: Sure, may I know your name please?

USER: Myself Donald Martinez.

ASSISTANT: Sorry Donald, there is no reservation found on your name.

USER: No problem, thanks for checking.

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

USER: Welcome.