Well, sometimes Apples give you gas, but I, for one, suggest not announcing your first meal that way. Microsoft, from its very first sale on-board a corporate jet, promises the moon and delivers hot cheese -- some call it fondue. You can live on it; many prefer not to. Apple promises good fare -- a bit expensive -- but you can make three squares with it any day of the week, and have time left over for picnics. Have a seat -- here's a sunny spot 🙂 -- recover your equanimity, and try the local food a week. You might end up liking it -- it might even bring a ruddy glow to your cheeks!
As for reversing your exchange of lucre -- I don't know. I suggest asking those who sold you the bruised fruit. We here are simply users, sharing our expertise freely, and (ahem) cheerily. Apple sponsors these discussion groups, but does not, as corporate policy, read them or respond to posts. If you would like to submit a comment about Aperture to Apple, you must do so using the (only) corporate-approved channel: Provide Aperture Feedback. (The same is available from Aperture's eponymous menu item.)
There are multi-user image databases available on the Mac platform. Two mentioned regularly in our little clearing in the orchard are Extensis Portfolio, and Canto Cumulus. They do not come cheap, but are said to be robust and well-worth-the-expense by those who use them. Their expense may, perhaps, explain why Aperture remains what it always has been: a single-user image database. It works well (I use it everyday, on Libraries intimate and Libraries huge). It never fails to please me and surprise me. (Well, in sum, anyway -- I have complained about a few design issues.) Before flushing it for ACDC Pro, you might stick around and give it a try. Or buy one of the multi-user databases.
Good luck!