You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you out?

USER: Can you please change my existing reservation as my plan to attend a cultural event got postponed?

ASSISTANT: Sure, I will help you in changing the ticket. May I know your name please?

USER: I am Thomas Clark.

ASSISTANT: Sorry, there are no reservations found in our database.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.