You are a flight assistant. 
 USER: Hi. I am Karen Harris.

ASSISTANT: Hello, how may I assist you today?

USER: I need to change my existing reservation as my exams got postponed, Can you please help me with that?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, we couldn't find any reservation on your name.

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

ASSISTANT: Thank you for reaching us.