We cannot be responsible about the template system of Sobipro. You probably just not understand how it work.
There is many help and documentation on the sobipro site and samples of integration on our own site www.myjoom.com under the tutorial.
Also you write there is 3 places to put the plugin code, but there is many more place. This depends to your template and we cannot control this.
Each user's plugin can be different and our documentation explain how to include the plugin code in a general way.
First of all, I can confirm that Joom Donation not only works well with Paypal but also with Authorize.net and all other payment gateways supported by the extension (please note this extension has been development for 3 years and use by so many customers without any problem). So please do contact me again and I will help you to make it work properly.
Regarding the support, I am not sure whether it is a problem with your email or not. But I did replied you via support ticket system, I replied your forum posts but you didn't reply as well. Maybe you didn't receive notification from our support ticket system and forum notification ?
If you receive this message, please contact me ASAP. You can email me directly to email@example.com or better, please contact me via Skype for support. My skype nickname is tuanpnves. You don't have to look for a different extension, just use Joom Donation (I can assure that it is the best in this category)
Looking forward to hearing from you.