I too cannot use Showtime after signing up with the Spotify student bundle. It's understandable that Spotify should assume that subscribers should be able to resolve this problem by contacting Showtime. However, so far this has not worked for me. I think Spotify should at least provide some basic information about how to make this process work properly.
Thank you for your suggestions. These specific instructions were not the solution to my problem but motivated me to continue. I solved my problem, but I can't tell you how I did it. If I could, I'd share it in case someone else experienced the same problem. Thanks again.