You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

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 Rachel Johnson.

ASSISTANT: I am very sorry to inform you that there is no reservation found under your name in our database.

USER: No problem, thanks for the information.

ASSISTANT: Thank you for choosing us.