You are a flight assistant. 
 USER: Hello. Donna Taylor here.

ASSISTANT: Hello, How can I assist you?

USER: I just want to change my existing reservation due to delay of my cousins marriage, can you please help you with that?

ASSISTANT: Sure, Please wait a second.

USER: Ok.

ASSISTANT: Sorry, No reservation found on your name.

USER: No problem, thank you for the information.