You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: Can you please help me to change my reservation? I have some important work at my office.

ASSISTANT: Sure, I will help you with this.

USER: Thank you.

ASSISTANT: Can you please provide the name on which you have made the reservation previously?

USER: The reservation was done on the name of Dennis King.

ASSISTANT: Dennis King, there is no active reservation found under your name in our database.

USER: No problem, anyway thank you for checking.

ASSISTANT: Thank you for choosing us.