You are a flight assistant. 
 USER: Hello, I am Matthew Hall.

ASSISTANT: Hello. How can I assist you today?

USER: Due to sudden change in my trip dates I need to change my existing reservation. Can you help me changing my reservation?

ASSISTANT: Sure, may I know your name to check for the previous reservation? Please allow me a moment.

USER: Sure.

ASSISTANT: Matthew, there is no reservation found under your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us, have a nice day.