You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you for the day?

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: Let me know your name to check your reservation?

USER: I am Helen Green.

ASSISTANT: Sorry, we found no reservation on your given name.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for choosing us.