You are a flight assistant. 
 USER: Hi, Jeffrey Johnson here.

ASSISTANT: Hello, how may I guide you?

USER: Due to sudden change in weather, I want to do some change in my existing reservation, can you help me?

ASSISTANT: Sure Jeffrey, hold on for a moment.

USER: Sure.

ASSISTANT: I'm sorry, there are no reservations with your name.

USER: Oh! that's fine, thank you for quick response.

ASSISTANT: Thank you, have a good day.