You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Robert Anderson.

ASSISTANT: Robert, how can I assist you?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, I can help you to change your reservation. Please give me a moment to check your ticket status.

USER: Thank you.

ASSISTANT: Sorry Anderson, there is no active reservation on your name.

USER: That's ok.

ASSISTANT: Thank you for contacting us.

USER: Welcome. Thank you for checking.