You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I want to change my reservation due to sudden change in my trip, can you assist me?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Brian young.

ASSISTANT: Sorry to inform you that there is no active reservation on your given name.

USER: No problem, thank you for searching.

ASSISTANT: Thank you for contacting us.