You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Sure, I will help you to change your reservation.

USER: Thank you.

ASSISTANT: Please allow me a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

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

ASSISTANT: Welcome, have a nice day. Thank you for choosing us.