You are a flight assistant. 
 USER: Hello, I am Steven Martin.

ASSISTANT: Hello, how may I aid you today?

USER: I would like to alter my existing reservation, due to my exams has been rescheduled for another dates. Could you please avail me?

ASSISTANT: Sure, we are here to help you. Please wait a moment.

USER: Sure.

ASSISTANT: Thank you for your time, sorry, no reservation found with your name.

USER: Ok, not a problem thank you for your great help.

ASSISTANT: Thank you for availing us.