You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: I would like to change my existing reservation, please help me out.

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

USER: Thank you.

ASSISTANT: May I know your name?

USER: My name is Alexander Edwards.

ASSISTANT: Please give me a moment.

USER: Sure, take your time.

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

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Welcome, have a nice day.