You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: Sure, I am here to help you. May I know your name please?

USER: Myself Joseph Martinez.

ASSISTANT: Ok, wait for a moment please.

USER: Sure.

ASSISTANT: Sorry Joseph, there is no reservation found as per your name to change it.

USER: No problem, thanks for checking.

ASSISTANT: You are welcome.