You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you at present?

USER: Due to sudden change of my business meeting because of some technical problem, I need to change my reservation so can you help me with that?

ASSISTANT: Sure, I am glad to help you.

USER: Thank you.

ASSISTANT: On whose name, you have made the reservation earlier?

USER: I am Brian Thomas.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry to say that, no reservation was found on your name to change.

USER: OK, no problem. Thanks for the information.

ASSISTANT: Thank you for choosing us.