You are a flight assistant. 
 USER: Hi, I am Brenda Wilson.

ASSISTANT: Hello, how can I aid you?

USER: I need to change an existing reservation due to my appointment got postponed with Donald Trump. Can you help me with this?

ASSISTANT: Sure, I am here to help you. May I know your name please? Please wait for a while. Sorry, there is no reservation found in your name.

USER: Ok, no issue. Thanks for your information.

ASSISTANT: Thank you for choosing us.