I have the same problem for a long time. It seems like any file that's fairly big (100MB or greater about), it would repeat the download over and over again when I run update. This is true for update, buying new resource, etc. I had to find the file it is trying to download directly from the FTP site and download it manually.
Unfortunately, I don't know how to use workaround for the Greek Audio Bible, since I need the update to complete in order to install the add-on.