You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Anna Evans.

ASSISTANT: How can I assist you?

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

ASSISTANT: Yes, I can help you. Sorry to inform you that there is no reservation found on your name.

USER: Thank you.

ASSISTANT: Thank you for contacting us.

USER: That's ok, no problem. Thank you for the information.