You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be at your service 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: May I know your name please?

USER: I am Donna Taylor.

ASSISTANT:  Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: No problem, thanks for the information.

ASSISTANT: Thank you for choosing us.