You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: My scheduled examination dates has been postponed.So, I would like to change my existing reservation which is under my name. Can you please help me with that?

ASSISTANT: Sure, I will help you in cancelling the ticket.

USER: Thank you.

ASSISTANT: Please, provide me your name to check your reservation?

USER: Sure, my name is Melissa Hill.

ASSISTANT: Sorry Hill, there is are no flights with your request.

USER: Ok, no issues.Thank you for checking.

ASSISTANT: No flight reserved on your name. Thank you for choosing us.

USER: You are welcome. Have a great day.