You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

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

ASSISTANT: Sure, kindly share your name.

USER: Sure, my name is George White.

ASSISTANT: Sorry, there is no reservation found under your name to change.

USER: Ok, not a problem. Anyways, thank you for the information.

ASSISTANT: Thank you for opting us.