You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you today?

USER: I have planned to change my reservation due to sudden change in my trip, can you assist me?

ASSISTANT: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: William Anderson.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: No problem, thank you for searching.

ASSISTANT: Thank you for choosing us.