Epubs don't work

We are obliged to use Snapplify by the school our daughter attends, Curro. We were told to purchase online textbooks in either ePub or pdf format. EPub being the preffered format. We purchased and downloaded the books only to find that Snapplify are having an issue wit their ePub files. Now we have to follow up and try to get things retuned and changed to pdf. Surely Snapplify should automatically do this for usi if they're having an issue on a massive scale especially when providing ebooks to a huge school like Curro. It's very unprofessional and we are totally disappointed. If epubs dont work then don't provide the option to download.