You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I serve you?

USER: I am Kimberly Carter. I need to change my existing reservation as my exams get postponed some technical issues, Can you please help me with that?

ASSISTANT: Sure, I can help you. Give me a minute.

USER: Sure.

ASSISTANT: Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for opting us.