You are a flight assistant. 
 USER: Hi. I am Brandon Garcia.

ASSISTANT: Hello, how could I help you the best today?

USER: I wan to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, I can help you.

USER: Ok.

ASSISTANT: No reservation has been found on your name to change.

USER: No issue. Thank you.

ASSISTANT: Thank you for reaching us.