I gather you're in the UK. Have you thought about contacting BBC Watchdog or Channel 4 Dispatches about your experience?
Given how litigious the organisation is, perhaps the 'cult' focus (and the common disparities in defining the term) is less helpful in raising awareness than shifting the attention to the lack of qualifications/credentials of the people involved or valid psychology research backing up their methods (these are facts that can't be argued against with a strawman). Or perhaps the parallels with MLM.
Also Baroness Jolly has been raising the broader issue of unregulated mental health practice in the House of Lords.