As per regulation R 181(1) put an application to Change of Conditions or Extend your stay in Canada as a Worker
This application is for temporary residents who are already in Canada and wish to:
extend the stay;
Change the conditions of your stay;
change your type of temporary status, that is from Working holiday to Student or
Correct problems with your status.
It is important to apply for the renewal before the expiry of your current status. Normally this is to be applied one month advance (which is considered OK), Mail your application, including all required documents and fees, to the Case Processing Centre (CPC) in Vegreville, Alberta. the application must have the following materials:
Application to Change Conditions, Extend My Stay, or Remain in Canada [IMM 1249]
Document Checklist [IMM 5556]
Fees Receipt
As per my suggestion, try second option i.e. restoration period option (Regulation 182 of IRPA), a protection regulation for the cases like your's who are in dilemma while in Canada on temporary work permit. You must apply for change of conditions within 90 days of expiry of the working holiday visa along with all essential documents. You need to convince CPC Officer, Vegreville, Alberta that you would like to stay in Canada as a student of post secondary student and also mention that so and so school/college ( with proper document of the school) has approved and given me preliminary admission and if you permit me then I would be able to make my future in canada by doing that program. Mention that I have to start my classes on so and so date and then you have apply for change of status from work permits to student visa. You have to make a plea of your case in a very sensitive way by drafting a nice forwarding letter from the experienced people mentioning the reason why did you not apply in advance( as per regulation of R 181) Mention your solid reason of failure to appy in time. I think you can say that I was in dilemma (that's true too) of whether I would be able to afford my studies in canada or not or think some other solid reason to explain why you entered in the position that you have to apply in the restoration period. In the end lines finish your letter with a remarks like this: now I am confident as my father/brother/ mother/ common law partner/ husband (who so ever you feel ok) has promised me to support if I will be in short of any funds in my studies. Now I need your permission, i.e. from CPC Vigreville, to consider my case sympathetically so that I would be able to make my life for future in Canada by achieving education in the field of ........ This approach looks slightly risky for you but some times work.
Third option you aleady know: go back to New zealand and then apply for student visa and get visa and join the institution very simple.
Best of Luck
