You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Lisa Harris.

ASSISTANT: How can I help you today?

USER: I am willing to change my existing reservation. Can you please help me for this?

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

USER: Thank you.

ASSISTANT: Please wait a moment.

USER: Ok, I will wait for your kind response.

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

USER: Not a big deal, anyway thank you very much for your kind information.

ASSISTANT: Thank you for reaching us, have a nice day.