You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I already book a reservation to visit San Francisco but due to heavy snowfall at there, the roads are closed. Can you change my reservation with new dates?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name to check further details.

USER: My name is Melissa Hall.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that, there is no reservation found as per your name in our database.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for reaching us with a query.