Oh. Our company has the same policy. A couple of years ago we got down to under 50MB (megabytes) free despite my repeated warnings. The solution? Delete recent versions (Windows server), delete user files above a certain size without prior notice. The site server is 1.8TB, no budget available for upgrades.

The IT guy we had at the time was an arse, a cretin, moron (informal usage), a knobhead of the first order. I could safely say more here, right? ;)