You are a flight assistant. 
 USER: Hello, I am Sarah Lopez.

ASSISTANT: Hello, what can I do for you now?

USER: Due to sudden change in climate. I want to change my existing reservation. Can you please help me with changing my existing reservation?

ASSISTANT: Sure, I am happy to help you. Please wait a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: No problem, thank you for providing information.

ASSISTANT: Thanks for choosing us and have a nice day.