I'm sorry that you (and so many other people) are having so many issues. The whole registration/code setup does seem to be very overcomplicated now. When it works it's great, but it would seems there's a lot of places for it to go wrong

The game itself is amazing and (hopefully) if you can ever get it work you'll agree, but I appreciate right now right now you're probably hating it with a passion.

I'm afraid all I can really suggest now is contacting SE, which is probably what you're already trying Good luck!