You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my reservation because my trip has been postponed. Can you assist me?

ASSISTANT: Sure, I can help you with that. May I know your good name please?

USER: Brian Clark.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Brian Clark, there is no active reservation found under your name to do changes in that.

USER: No problem, thank you for helping me.

ASSISTANT: Thank you for choosing us.