You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you for today?

USER: I am Nancy Martinez.

ASSISTANT: Ok.

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

ASSISTANT: Sure, I will change your reservation. Please wait for a while.

USER: Sure.

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

USER: That's fine.

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

USER: Thank you for your service.

ASSISTANT: You are welcome.