You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: How may I assist you today? Sure. May I know your name?

USER: I am Daniel Anderson.

ASSISTANT: Sorry, we haven't found any reservation based on your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thanks for contacting us.