You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please allow me a moment.

USER: Ok, take your time.

ASSISTANT: Sorry, there is no reservation found to change further.

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

ASSISTANT: You are welcome.