You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am William Anderson.

ASSISTANT: How may I assist you?

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

ASSISTANT: Sure, I am here to help you out. Wait a moment please.

USER: Sure, I will wait for your response.

ASSISTANT: William Anderson, we haven't found any reservation under your name in our database.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for choosing us.