When someone is linking to a paid link, or posting about a product by charging the product owner he kills the whole PageRank concept. As in theri case they are helping the paid blogs to have high PR by charging them.
If you think that your intentions were right, and you were showing paid-links on your blog just for driving traffic to the other website, you can get your old PageRank back very easily.
Google isagainst the the sharing of PR and not against paid post.
You have to do only two things if you have Paid links on your blog:
First, label all your paid posts as "Sponsored reviews" or disclose it on every post, not just a site wide disclosure policy, Second, put the "nofollow" tag on the sponsored links in your post which should look like this: Sponsor's anchor text.
Above two steps will make sure google BOT is not mislead.
Next, log in or join Google's Webmaster Tools. On the right side of your dashboard you will see a request reconsideration link. Press that, submit your site, and explain that you have already made changes on your site so that it conforms with Google's Quality Guidelines, a small request or apology will work too. Wait for few days and you will see that your PR is back to normal and your posts are relisted in Google search