You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name please to check your previous reservation status?

USER: My name is Jessica Lopez.

ASSISTANT: Jessica Lopez, no reservation has been found on your name in our database.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.