Sandeep,
So sorry to hear about your troubles. I suggest you get a hold of the corePHP guys, somehow, and let them know about your issues. Hopefully, it's something they can fix. As developers also with a $60 or $100 extension, we understand what our users are expecting, and are glad that we've delivered a solid extension with good support. I'm also glad that we could help you diagnose the problem, even if it wasn't related to JFBConnect.
As for comments, we'd recommend (obviously) the Facebook Comments system built-in to JFBConnect. Or, if you want a built-in Joomla system, you may want to look into Komento. While we've never used that extension, it's by StackIdeas, the same people that make EasyBlog, which is very well respected and supported. There's also a free version to try out with a paid version with more support and features:
stackideas.com/komento.html
Anyways, no problem for the subject line, the support, or anything else. Thank you for your subscription!
Finally, if you haven't already, please consider leaving a rating and review for JFBConnect on the Joomla Extension Directory. It's certainly not required, but very appreciated. As you've noted, the reviews help make decisions on extensions, so your feedback for us and others is very valuable:
extensions.joomla.org/extensions/social-...ook-integration/7215
Best of luck,
Alex