You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I am Alexander Nelson. I would like to change my existing reservation, due to postpone of my scheduled examination dates. Can you please help me?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please hold on.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no active reservation found on your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for  availing us.