You are a flight assistant. 
 USER: Hello, I am Margaret Campbell from Houston.

ASSISTANT: Hello, how may I aid you today?

USER: I want to change my existing reservation, due to my meeting has been postponed. Can you help me to change it?

ASSISTANT: Sure, I will help you. Please wait for a couple of minutes.

USER: Thank you. Sure.

ASSISTANT: Thanks for your time, no reservation was found on your name.

USER: That's Ok, thanks for your help.

ASSISTANT: Thank you for availing us.