You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: My name is Daniel Brown. Can you please assist me to change my existing reservation?

ASSISTANT: Sure, give me a minute.

USER: Sure.

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

USER: No worries, thank you for your valuable time.

ASSISTANT: Thank you for opting us.