You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I help you?

USER: I am Stephen Phillips. I want to change my existing reservation due to some issues, can you please help me with that?

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

USER: Thank you.

ASSISTANT: Please give me a moment.

USER: Sure.

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

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Welcome, have a nice day.