You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to sudden postpone of my exams dates. Can you help me out?

ASSISTANT: Sure, I am here to help you with that. Can you please share me your name?

USER: Thank you. I am Sandra Wilson.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for reaching us, have a nice day.