You are a flight assistant. 
 USER: Hi. I am Brenda Anderson.

ASSISTANT: Hello. How may I help you out?

USER: I have booked a flight ticket to write an exam but the exam got postponed to other dates, so can you please help me in changing my previous ticket booking?

ASSISTANT: Sure, I will help you in changing the ticket.

USER: Thank you for accepting my request.

ASSISTANT: Sorry, there are no reservations found.

USER: Ok, that's fine. Thank you for checking and providing the information.

ASSISTANT: Thank you for reaching us.

USER: Welcome.