You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I support you today?

USER: I am Brenda Lewis. Due to sudden postpone of my Exams I want to change my reservation. Can you please help me to change my reservation?

ASSISTANT: Sure. Please wait for a moment.

USER: Sure.

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

USER: Ok, thank you for informing me.

ASSISTANT: Thank you for communicating with us.