Is the future 7 or is it 8/8.1?
With MS, the future is always <current OS Version>+1 ... even when they use silly names (like "Vista").
The situation is confusing right now because MS is modifying Win8+ to restore features that they initially removed with the deployment of Win 8.
Some would say this is trying to make it more like Win7. But others, including me, will say that in using the Desktop Mode, the Win7 "look and feel" was there all along. All MS is doing is making the Desktop Mode easier to get to, and more of a default.
Personally, I continue to be astounded by folks who rant on about "Hating" Win8, when in fact, all they really dislike is the tiles-UI. That takes only a few minutes to change, and with the every changing landscape of Win8+, it's going to be easier to do with each "upgrade".
It's very unlikely the store will take it back. Every place I buy software from has a strict "open-the-box-and-you-bought-it" approach in denying returns. And, if as you imply, you've had this for over 40 days, that's even more reason for them to refuse to take it back.
I would go along with others and suggest you give it a try. You can use Desktop Mode as your default, if that is more familiar to you, but you should also try the tiles-UI. You might grow to like it -- they are making it "better" (IMHO) with each "upgrade".