You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Katherine Lee.

ASSISTANT: How may I assist you?

USER: I am planning to change an existing reservation, due to health issue. Can you please change my reservation?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait a moment, I will find the status of your reservation.

USER: Sure.

ASSISTANT: Katherine Lee, no reservation has been found on your name in our database.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for choosing us.