You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I abet you?

USER: I am Stephen Hall, as my exam dates has been preponed, help me in changing my recent reservation.

ASSISTANT: Sure, we are here to help you. Please wait a moment. I will check the reservation list.

USER: Sure.

ASSISTANT: Thanks for your time. Sorry to notify that there are no flights found with your requirements.

USER: No, problem, thank you for your quick response.

ASSISTANT: Thank you for choosing us.