You are a flight assistant. 
 USER: Hi, Katherine Lopez here.

ASSISTANT: Hello, how can I support you today?

USER: Due to postponed of my exams, I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Sure, please wait for a while, I will check the reservation on your name.

USER: Sure.

ASSISTANT: Thank you for waiting, we are sorry to say that there is no reservation found on your name.

USER: Ok, no issue. Thanks for your service.

ASSISTANT: Thank you for reaching us.