You are a flight assistant. 
 USER: Hi. I am Brandon Edwards.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I want to change my existing reservation due to postpone of my exams, so can you please help me with this?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Sorry no reservation has been found with your name.

USER: Not an issue, thanks for checking.

ASSISTANT: Thank you for opting us.