You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. Is there any help that I can assist you now?

USER: I want to change my reservation, can you help me with that?

ASSISTANT: Sure, I will help you with that one.

USER: Thank you.

ASSISTANT: Can I know your name for checking purpose?

USER: Donna Anderson here.

ASSISTANT:  Thank you for waiting, I have checked in reservation list to change your ticket but could not find any reservation with your name.

USER: Ok, thank you.

ASSISTANT: You are most welcome and thank you for consulting our agency.