You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,.

USER: I am Brandon Brown.

ASSISTANT: How can I assist you today?

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

ASSISTANT: Sure, we are here to aid you.

USER: Thank you.

ASSISTANT: There is no reservation found on your name Brandon Brown.

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

ASSISTANT: Thank you for opting us.