You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I do for you?

USER: My business trip has been postponed.Can you please help me for changing the existing reservation?

ASSISTANT: Sure, I am here to help you only. Can I know your name, please?

USER: Thank you. Sure I'm Sharon Smith.

ASSISTANT: There is no reservation found for you, Sharon.

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

ASSISTANT: Thank you for using our service.