You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation, as my exams have postponed suddenly. Can you please help me ?

ASSISTANT: Sure, may I know your name please?

USER: I am Karen Perez.

ASSISTANT: Sorry, there is no reservation with your name to change further.

USER: Ok, not an issue. Thank you for your time.

ASSISTANT: My pleasure.