I've used Dropbox since literally their first year of creation and I've never experienced a single one of these issues. I use it mostly as a portable library and all I need is 2 mins of any internet connection to download any book(s) I want to read to a local device. Mind you this is on their free plan, so I've never paid a cent to them either. Requires me to periodically transfer older books to another long term solution, but that is just a few mouse clicks. I've read hundreds if not more ebooks this way. Since I prefer .mobi (which I can even read IN dropbox if I want) I can upload straight to dropbox after converting from .epub.

I mean, it sounds frustrating, but your experience with them sounds extremely weird to me.

At least to me they've been the best cloud provider by far, for what it's worth.

With that said, I don't especially like that they're doing this even though my specific content is mostly available in any number of places anyway, given that it's literature.