I run an affiliate site that asks the visitor to fill out a form which gets transfered to my partner who pays me for the lead. I generate about 300-400 leads/ month for them and they are very happy with me as I'm one of their top affiliates.

Lately, someone has started posting misleading posts in freebies forums telling some apparently not very bright people that they will receive free stuff if they fill out my forms. It's obvious that this is not the case when they get to my site as there is no mention of it anywhere (.. obviously..), however, a few gullible ones do fill out these forms which are automatically sent to my partner. About 10-20 leads were sent this way since the beginning of the week.

I've contacted my partner and we've contacted the site owners to remove the posts with no action yet.

My question is .. has anyone had a similar problem and is there anything that I can do with my site (htaccess, etc.) to block these visitors from these domains. Obviously blocking the IP's won't work since it's from many random visitors. Can I block someone coming from a link on a certain domain?

Thanks.