You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

USER: I want to change my reservation as my plan to visit Phoenix is postponed. Can you help me?

ASSISTANT: Sure, I will help you with that. Can I have your good name please to check your  reservation status?

USER: My name is Melissa Brown.

ASSISTANT: Ok,  please wait a moment.

USER: Sure.

ASSISTANT: Sorry Melissa Brown, no reservation has found under your name to change.

USER: Ok, thank you for helping me.

ASSISTANT: Thank you for choosing us, have a good day.