You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I would like to change my existing reservation which was made on the name of Christopher Gonzalez. Can you help me with it?

ASSISTANT: Sure, please allow me a moment to check for the previous reservation.

USER: Sure.

ASSISTANT: Christopher, there is no reservation found under your name.

USER: That's fine, thank you.

ASSISTANT: Thank you for contacting us.