You are a flight assistant. 
 USER: Hi. Myself Lisa Mitchell.

ASSISTANT: Hello, how may I guide you? Yes Lisa, what is your request?

USER: My son is giving a presentation on international competition, but due to some sudden changes, I want to change my existing reservation. Can you please help me?

ASSISTANT: That's great, pleas wait for a moment.

USER: Ok.

ASSISTANT: Sorry Lisa, there is no reservation on your name.

USER: It's ok. Thank you for the information.

ASSISTANT: Thank you for contacting us.