As I said difficult to say much without being specific to the case but it's not the sort of job that has professional bodies. Not sure about the insurance one but I ll suggest it.
Lots of evidence in form of letters, emails, recorded 'incidents', etc. but its knowing what to do with it, if indeed there is anything that can be done... a few solicitors from the Yellow Pages were tried but all were non-commital on advice or potential outcome until money paid. CAB gave some general advice but said they were out of their depth and could only really advise contacting solicitor..
PW