You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I serve you?

USER: Frank Robinson here. I want to change my existing reservation due to postpone of my exams. Can you help me in that?

ASSISTANT: Sure, Please wait a second.

USER: Sure.

ASSISTANT: Sorry, No reservation found on your name.

USER: Ok, not an issue. Thank you for giving information.

ASSISTANT: Thank you for opting us.