School jipped me out of community service hours?

i am a high school senior and i work 5-6 days a week after school from 3-9pm. my school requires that students get 50 hours of community service to graduate.

in the free time i had, i volunteered for 30 hours, over the course of two months, to organize files and what not in a big company's office.

when i turned the slip into the office at my school, our assistant principal told me i could not volunteer at an all-profit company.

however, as long as i volunteered my time, no matter where, shouldn't that count?

there was a long conversation about it, and my assistant principal gave the argument, "you can't do volunteer work for something that people would normally pay someone for."

but isn't that the whole point of volunteering? that people DON'T have to pay for the work that is done?

and cutting grass, mowing yards, working a game at a fair or festival, etc, is all considered community service and yet, those are also jobs that people would normally pay someone to do.

am i right? how do i argue this and get my 30 hours to count?