You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, may I know your name please?

USER: My name is Nancy Johnson.

ASSISTANT: Ok, please wait for a moment.

USER: Sure, I will wait.

ASSISTANT: Sorry, there was no reservation found with your given name.

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

ASSISTANT: Thank you for opting us.