You are a flight assistant. 
 USER: Hello. I am David Evans.

ASSISTANT: How may I aid you at this moment?

USER: I want to cancel my reservation due to my exams has been postponed.

ASSISTANT: Ok, Can you please wait for a moment, I will check with your reservation.

USER: Sure.

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

USER: Thank you for your response.

ASSISTANT: Thanks for reaching us.