You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

USER: I want to change my existing reservation, as my exams got postponed. Can you please help me out with it?

ASSISTANT: Sure, I am happy to help you with that.

USER: Thank you for the response.

ASSISTANT: Can I have your good name please to check your reservation status?

USER: Myself Mary Brown.

ASSISTANT: Ok, please wait  a moment.

USER: Ok, sure. I will wait for your response.

ASSISTANT: Sorry Mary Brown, no reservation has found under your name to change.

USER: Ok, not an issue. Anyways, thank you for the information.

ASSISTANT: Thank you for choosing us, have a good day.