In case anyone from Anime Limited reads this thread, I hope the following feedback is helpful.
I've had one box set and two BOGOF titles in my basket for a while now, waiting for short-notice items to appear in the sale so I can get the total to £50 for free shipping.
I just got the Great Pretender box set - but of course, I can't use the 10% code on it (and the other box set I'm buying), because the code doesn't work on the BOGOF items. So in the end, I removed the two BOGOF disks so that I can apply the code just to the two box sets. In other words, sadly you lost a purchase from me because of the limitations of your system (or at least, the third party you use).
I hope you'll be able to use this knowledge to drive some positive change at the purchasing stage, because sadly you're losing money due to the current system.
(As a PS to that idea, I would like the BOGOF to be smart enough to match price-for-price titles. For example, if I have eight £10 BOGOFs and two £20 BOGOFs, I'd like one of the £20 ones to be discounted. At the moment it only matches on cheapest price. Sadly, all this does is make me remove the two £20 ones - so again, you lose a sale. At best, I have to remove the two £20 ones, and hope that I can then buy them again later as part of a second order - but then I run into the problem of not being able to use the code on that order because of the BOGOF items.)
Finally, in other threads I've mentioned an idea of giving buyers the option to "buy now, ship at the end of the sale" so that everything can be combined into one single package. This gives a ton of advantages, including cheaper costs for you and for us on shipping, as well as being better for the environment. It also fixes the BOGOF problem above, and is even a potential workaround to the discount code problem. I hope you'll consider it for the future.