You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Due to an emergency, I want to change my reservation. Can you help me?

ASSISTANT: Sure, I will help you to change your reservation.

USER: Thank you.

ASSISTANT: Ok, may I know your name?

USER: Joseph Anderson here.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: No problem, Thanks for the information.

ASSISTANT: Welcome, have a nice day.