Hi! Have you tried re-downloading it? Music can't be re-downloaded in all countries, but if available, try deleting the incomplete tracks from your iTunes library and following the instructions in the link to Redownload them fresh. Otherwise, you can use the "report a problem" feature by finding the download in your purchase history. iTunes support is really effective in my experience, though these days it may take a little time. YMMV. Of course, you could always request a refund and start all over, but usually the previously mentioned steps resolve the problem and that's rarely necessary. In my experience. Rest assured, one way or the other, you will be the champion, my friend.
Good luck!
-- JDee