I bought mine off eBay as well and also had problems with registering the device. Have you registered with
eBookwise yet? I find that they will answer emails and although I never any technical issues to ask them, they were prompt.
Try to go through eBookwise and try that method. If you can download a free version of a book from their site, everything should be working for you from then on.
Actually, I have had some problems recently in downloading from their site. I have to retry the download over and over until it catches. I don't know why.
Just noticed that their site is down. That has never happened to me before. Maybe that is your problem.