You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: I am Patrick Hernandez. I want to change my existing reservation.Can you help me in this?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Sure.

ASSISTANT: We regret to inform you that there is no reservation found on your name in our records.

USER: Not a problem, thank you.

ASSISTANT: Thank you for reaching us, have a great day.