You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Yes, I can help you. Can you tell me your name for checking?

USER: Yes, I am Joseph Lee.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Ok, not a problem.

ASSISTANT: Thank you for contacting our agency.

USER: Thank you for your information.