You can go download the official DMG of whatever version you purchased if you want. BundleHunt is usually just offering it as a convenience for purchasers.
FWIW, I’ve found that the best mental framework for looking at software purchase is that it’s completely non-refundable unless explicitly stated otherwise.
I would agree that they should at least reply to you to tell you’re out of luck though. 
That said, I did manage to get a refund from them for software once that just outright wouldn’t install.
They have some back-end magic where they communicate purchases to the devs, and the devs issue licenses. I’ve emailed devs directly at a later date about software I bought from BundleHunt, and they never have problems finding license codes or anything. And I’ve never been treated like a second-class citizen because I bought it through BundleHunt.
My only caution is that a lot of apps have confusingly-similar names and icons. BundleHunt doesn’t ever outright misrepresent things in my experience, but always double-check what exactly you’re buying before you buy it.