You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am William Gonzalez. I just want to change my recent reservation.

ASSISTANT: Sure, let me check.

USER: Ok.

ASSISTANT: Thank you for waiting. But sorry, there is no reservation found for this search.

USER: Thank you.

ASSISTANT: Thank you for contacting us, have a good day.