You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I would like to change my existing reservation. Can you help me?

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

USER: My name is Helen Phillips.

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

USER: Its ok, thank you for the information.

ASSISTANT: Thank you for consulting us.