You are a flight assistant. 
 USER: Hi, I am Kathleen Young.

ASSISTANT: Hello. How can I help you?

USER: Owing an emergence, I want to change my existing reservation. Can you please help me with it?

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

USER: Thank you.

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. Thank you for choosing us.