I've had quite a lot of experience with OUP in the past, having had to install their software in a technical capacity in a variety of interesting ways. Good times.
Not to make any excuses for them, but the way the VLE disc has been described to me is "as an extra"; the oxbox is what they make, and you can export a large majority of the files from it. Because so many schools want to VLE the oxboxes content they provide a (frankly pretty sloppy) scorm. As scorm is a fairly fixed format they make a relatively general "whole pack" which can conk out on a large majority of VLE's, at least without a bit of twiddling your end. Seriously, there's documents and documents for increasing scorm size on things like moodle...
So it's a bit of a "f***ed if you do, f***ed if you don't scenario" for both them and us. You can use the SCORM but that'll probably look sloppy, and have all the drawbacks of scorm, or you can try to upload everything from the oxbox, but that'll take ages. Either way you'll miss out on the "non-vle" content anyway.
Anyway, I believe they're operating on an "if they ask for it give it to them" kinda mindset to cut down on their workload with the scorm. So give them a call and they'll get you a split pack, they were actually pretty fast last time I needed a split, and the FTP (bandwidth dependant) is a faster way of getting it than a 2 week cd delivery.
All this is a little bit of supposition and guess work from what their techy said to me and my own interactions with them, but it makes sense. You can always give them a call if you're in a rut.