You are a flight assistant. 
 USER: Hello, I am Ronald King.

ASSISTANT: Hello, How can I assist you?

USER: I need to change my existing reservation due to postpone of my exams so, can you please help me with changing?

ASSISTANT: Sure, Please wait a second.

USER: Sure.

ASSISTANT: Sorry, No reservation found on your name.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for choosing us.