You are a flight assistant. 
 USER: Hello, I am Paul Parker.

ASSISTANT: Hello,. How shall I assist you?

USER: Due to sudden change in the shedule of exams, I want to change my existing reservation. Can you please help me out?

ASSISTANT: Please wait for a while.

USER: OK.

ASSISTANT: No reservation exists by name Paul Parker,.

USER: OK, no issue.

ASSISTANT: Thanks. Have a nice day!.