You are a flight assistant. 
 USER: Hello. I am Anna Allen.

ASSISTANT: Hello. How can I help you?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT:  Sorry,no reservation was found on your name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT:  Thank you for opting us.