This taken from the front page where you purchased the plugin:
Subscribe2 HTML provides all of the features of Subscribe2 with the addition of:
- Sends HTML emails sent to all confirmed public subscribers
- Has the ability to send HTML emails from Post->Mail Subscribers
- Sends Digest Emails containing HTML
That is an exact description of what your were buying and downloading. You CANNOT do these things with the free version.
What additional documentation do you feel you want or need with the code? It works exactly the same as the free version - which includes a PHP guide in the install folder, has FAQs here, a forum on GetSatisfaction and a dedicated announcement site with lots of documentation like FAQs and troubleshooting tips here.
I note you also asked a question at the WPPlugins forum site which was answered within an hour of you posting it.
You are fully entitled to your opinion and if you think it's a waste of money that's fine but don't accept 'terms and conditions' of a sale and then tell me how awful that is when you don't like what you bought. After all you have now wasted my time responding to you on two different forums all because you could not be bothered to read up thoroughly before buying.
If I were to refund you any money how am I ever to know that you are not still using my code for free - you downloaded it and could have created numerous copies and placed it on several servers by now. This is why there are no refunds.