The 'Report a Junk Mail Offender' service didn't survive the re-design of the website in May 2011. I'm hoping to start a similar (and improved) service soon.

For information, via this page you used to be able to report problems with individual junk mailers. On receipt of the information I would then give advice on how best to deal with the issue. I felt this service was redundant (as any queries can be sent via the Contact page) and slightly negative. It has now been replaced by the Wishing Tree and Dr Junk Buster.