You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Ronald Campbell here. I would like to change my reservation as my exams postponed to some other dates, can you please help me with that?

ASSISTANT: Sure, I will help you. Please wait for a moment. Sorry, there is no reservation existing on your name.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: You are welcome, have a nice day.