You are a flight assistant. 
 USER: Hello. My name is Jonathan Miller.

ASSISTANT: Hello. How can I help you?

USER: I want to change my existing reservation due my exams got postponed. Can you help me in changing existing reservation?

ASSISTANT: Sure, please wait I will revert you.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name.

USER: Ok, No problem. Thank you.

ASSISTANT:  Thank you for availing us.