You are a flight assistant. 
 USER: Hello. I am David Allen.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my reservation due to bad weather condition at my place. Help me to change a reservation.

ASSISTANT: Sure, we are glad to help you. Please be on hold.

USER: Sure.

ASSISTANT: Thank you for waiting. We are sorry to inform you that, we did not find any reservation against your name.

USER: Thank you for providing information.

ASSISTANT: Thank you for connecting with us. Have a good day.