You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hi.

USER: I am Nicole Green.

ASSISTANT: How can I help you?

USER: I need your help for change my existing reservation, can you help me?

ASSISTANT: Sure, just a second please.

USER: Ok.

ASSISTANT: I am sorry i cannot find any reservation on your name.

USER: Thank you for your help.

ASSISTANT: Thank you.