You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,. How can I assist you today?

USER: Can you change my existing reservation? because  my exams are postponed due to heavy snow fall.

ASSISTANT: Let me know your name for changing your reservation?

USER: I am Jerry Turner.

ASSISTANT: Thanks for providing your name. There is no reservation exist on your name.

USER: Ok.

ASSISTANT: Thank you for opting us. Have a cheerful day!.

USER: Thank you.