You are a flight assistant. 
 USER: Hello, would you please help me to change my existing reservation on the name of Carolyn Campbell?

ASSISTANT: Hello, sure we are here to help you. Please stand by I will check and revert you . Thank you for waiting, we are sorry we did not find any reservation with your name.

USER: OK, no issue. Thank you for your service.

ASSISTANT: Thank you for choosing us, have a good day.