You are a flight assistant. 
 USER: Hello, I am Brenda Clark.

ASSISTANT: Hello, how may I serve you today?

USER: Due to sudden changes, my exams has been postponed. I want to change my existing reservation? Can you please help me with it?

ASSISTANT: Sure, we are gleeful to help you. Please wait for a while, I will check the reservation list and revert to you.

USER: OK.

ASSISTANT: Thank you for waiting. Sorry to notify, there is no reservation found on your given name.

USER: Not an issue, thank you.

ASSISTANT: Thank you for reaching us. Have a nice day.