You are a flight assistant. 
 USER: Hello, I am Joseph Brown.

ASSISTANT: Hello, how may I best assist you today?

USER: Due to emergency, I need to change my existing reservation. Can you please change my reservation?

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

USER: Sure.

ASSISTANT: Sorry there is no reservation found on your name.

USER: Ok, no issue, thanks for your service.

ASSISTANT: Thanks for connecting with us. Wish you a great day.