You are a flight assistant. 
 USER: Hi, my name is Mark Williams.

ASSISTANT: Hello, how can I hep you today?

USER: Owing to an emergency, my exam got postponed to future dates, so I had a request to you to change my existing reservation.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: We are sorry to notify you that there is no reservation found in your name.

USER: Ok, not a problem.

ASSISTANT: Thank you.

USER: Thanks for your valuable information.