Well, let's fix your USB drive first but what you could try afterwards: Delete both, the game and the DLC with NUSspli (this is important as data management won't delete tickets but we want them to get removed). Then try to download and install both with NUSspli, too. This might take more time than USB Helper but maybe it works?
On a side note:
https://github.com/Xpl0itU/WiiUDownloader/releases is the new USB Helper, so better use that.