You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to change my existing reservation. Can you please help me in that?

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

USER: Thank you.

ASSISTANT: Can you please share me your name?

USER: Myself Kathleen Clark.

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

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

ASSISTANT: Welcome, have a nice day.