You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Anna King here.

ASSISTANT: How can I help you?

USER: Please change my existing reservation which I have done previously.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: There is no reservation found on your name.

USER: It's ok, thanks for your help.

ASSISTANT: Thank you for reaching us.