Digital ebook provider says I have used all my devices so cannot have my ebooks

I have purchased eBooks from Kalahari and then Takealot over the last 6 or 7 years. During that time I have moved from iPad to iPad and Mac to Mac, deauthorizing and then reauthorising, always using the same ID.

All of a sudden on my last iPAD, when I tried to get these books again, I wasnt able to. I kept receiving either "token not available" or a "Fulfillment error 0". On checking, they told me to download to Digital editions. I did this but then received the ""E_LIC_ALREADY_FULFILLED_BY_ANOTHER_USER" error.

According to Takealot, this is my problem as they will not reset anything to allow me to access these eBooks. Their reasoning is that I only borrowed them and I only borrowed them for the original devices so I should expect to have them on my new devices. For me to get these books, I would need to buy them all over again!

A couple of books have downloaded perfectly, and those are mostly the more recent ones - which were probably purchased on a later device.

Is anyone able to assist me? It doesn't seem fair that only a certain number of devices are allowed to be used, or that if I de-authorise one, I am not allowed to authorise the newer one. I have also moved from SA to the UK, but even during that move, I have NOT changed my user id.

Any advice???