You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Thomas Carter.

ASSISTANT: Can I know for what service you reached us?

USER: I am planning to change my reservation.Can you please assist me?

ASSISTANT: Sure, I will definitely help you Carter.

USER: Ok.

ASSISTANT: Carter, there is no reservation with your requested information.

USER: Ok, thank you for your services.

ASSISTANT: Thank you for choosing us.