PPC fraud has been a problem for me as I am in a very competitive field. I have had some success recently in that one of the PPC engines, having identified the problem, have blocked some IP addresses so that I dont get charged when they click on my site. This has worked and cut my spend in half. I use several PPC engines and would obviously like to do the same with the other ones. However, the PPC engine that has blocked these IP addresses is refusing to let me know what they are so that I can pass this on to the other PPC engines. Whilst I can see that they may not want to effectively assist one of their competitors, is there any real reason for them not to give me this information, and how can I persuade them to do so?