In 2004 there was a newspaper story about a Mr Cook who was taking the CSA to the European Court of Human Rights for compensation for the differance of +£100 a month in the maintenance calculation of the 2 formulas. He was using a solicitor called Cameron Fyffe from the Glasgow solicitors Ross Harper.
http://news.scotsman.com/childsupportagency/CSA-facing-human-rights-claim.2549747.jp
Does anyone know what the result of this challenge was or if it even got to court? There must be thousands of people with the same problem.