A VOC doesn't change the expiry date of your current visa. So if you're on a 1-year work visa it would be more beneficial to apply for a whole new work visa, as I guess your current work visa is also running out of time soon.
As you already graduate in 2013, I'm afraid the study-to-work (employer-assisted visa for new graduates) category isn't suitable. I'm no expert but I think it's likely that your employer needs to advertise the role on trademe to prove no NZ residents are available.
Good luck and Merry Xmas!