You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I am Stephen Hill.

ASSISTANT: Yes, Hill.

USER: I want to change my previous reservation, can you help me?

ASSISTANT: Sure, please wait a moment. Sorry Hill, no reservation found on your name in our data.

USER: It's fine. Thank you for your immediate response.

ASSISTANT: Thank you for reaching us.