You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. What assistance that you expect from us?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me with this change existing?

ASSISTANT: Sure, may I know your name for checking purpose?

USER: I am Kevin Hall.

ASSISTANT: Please hold on for a moment.

USER: Ok.

ASSISTANT: There is no reservation found on the name which you have provide to modify it.

USER: No issue.

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

USER: I will choose another alternative. Thank you.

ASSISTANT: Most welcome.