You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation due to postpone of my exams, can you help me with that?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Can I have your name to check for earlier reservation?

USER: My name is Barbara Johnson.

ASSISTANT: Please, hold on a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, I did not find any reservation on your name to change.

USER: No problem, thank you for the checking.

ASSISTANT: Thank you for availing us.