You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you at this moment?

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

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Joshua Evan.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Sorry, we could not find any reservation on your name in our database.

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

ASSISTANT: Thank you for choosing us.