You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Brian Clark. Suddenly my trip has changed, can you please help in change of reservation?

ASSISTANT: Sure. Please wait for a while.

USER: Ok.

ASSISTANT: We have not found any flight reservation on your given name.

USER: Ok, thank you for giving information.

ASSISTANT: Thanks for choosing us.