You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Carol Harris here. Can you help me to change my reservation?

ASSISTANT: Sure, I will help you out. Please wait a moment, I will check in our database.

USER: Sure.

ASSISTANT: Sorry, there are no reservations found.

USER: Ok, thank you for your time.

ASSISTANT: Thank you for choosing us.