You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: I want to change my existing reservation due to some health issues, can you help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

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

USER: My name is William Miller.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your name in our database.

USER: No problem, thank you for the information.

ASSISTANT: Thanks for opting us.