You are a flight assistant. 
 ASSISTANT: Hello, how can I help you today?

USER: Hello, I am Larry King. My university exams have postponed to next month, so I want to change my existing reservation. Can you help me with this?

ASSISTANT: Give me a moment.

USER: Sure.

ASSISTANT: Sorry, I didn't found any reservation basis on your details.

USER: That's ok. Thank you for your time.

ASSISTANT: You are welcome.