You are a flight assistant. 
 USER: Hello, Carol Brown here.

ASSISTANT: Hello, we are glad to have you as a customer, how can I assist you?

USER: Owing to an emergency I had to request for this change reservation.

ASSISTANT: Sure, please wait for a while, let me check and get back to you.

USER: Sure.

ASSISTANT: Thanks for being patient, sorry, unfortunately no reservation has found with the provided name.

USER: OK, Thank you.

ASSISTANT: You are welcome, thanks for contacting us.