You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you today?

USER: Could you please change my existing reservation due to postpone of my exams?

ASSISTANT: Sure, I am here to help you with this. May I know your good name please?

USER: My name is Rebecca Hernandez.

ASSISTANT: Ok, wait for a mean while.

USER: Sure.

ASSISTANT: Sorry to say, that there is no active reservation found on your name to change it.

USER: Not a problem, thank you.

ASSISTANT: You are welcome.