You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: Can you change my existing reservation? Because I postponed my trip due to ill health.

ASSISTANT: Ok, please share your name.

USER: I am Carol Lewis.

ASSISTANT: Wait a minute.

USER: Sure.

ASSISTANT: Sorry, we could not found any reservation on your name. Sorry, there is no reservation found on your name.

USER: Thank you for your information.

ASSISTANT: Thank you for choosing us.