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

ASSISTANT: Hello Mitchell, how may I guide you?

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: Sure, wait a moment to check your previous reservation status.

USER: Ok.

ASSISTANT: Sorry Mitchell, we don't any reservation under your name.

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

ASSISTANT: Thank you for using our service, have a nice day.