The most important action you can take is to report any further harassment and threats to the police the moment they happen and insist upon receiving an incident number. This builds up a case that can be used in court.
Of course, all that is needed is for a couple of police officers to visit the aggressor and inform him that he will be charged and prosecuted if any further incident occurs. This almost always works and it is amazing that the police can seldom be bothered to make a visit to nip trouble in the bud.
You can contact the Independent Police Complaints Authority
http://www.ipcc.gov.uk/en/Pages/default.aspx to complain that the behaviour of the police has undermined public confidence in them.
You have also done the right thing by contacting councillors. Perhaps you should write to your MP summarising the situation and asking if this would result in disciplinary proceedings against the police and those from whom you have sought support if you were attacked (submit a brief note and attach supporting evidence).
Document everything and ensure that as many people as possible know about it.