So, if I may (inexpertly) summarise:
1.This organisation has been blocking publications, jobs, consultancy, promotion etc to those whose supposed political views it dislikes. It has destroyed friendships. It has been clandestinely recording conversations of the victims and I believe using selective quotations to put them into an extremely adverse light. There is obviously financial loss and reputational damage. It is, finally, quite possible that these activities will results in physical illness, breakdown and even suicide of victims.
2. The only legal redress available to the victims consists of a charge of Harassment or possibly slander/libel. H is only available if the harassment is committed by individuals and if there is legally admissible evidence available to support it. This cannot be supplied by email hacking but witness testimony might do the trick.
4. This would be pursued as a civil action and might result in an injunction against the individual but not in damages or imprisonment. It would also be costly and it might be necessary to repeat the process if another member of the organisation were to replace the first, and so on.
5. There is a problem if the witnesses to this harassment refuse to testify in court as these may be subject to the same H themselves and without their testimony not even an minimal redress in the form of an injunction can be obtained. Such witnesses cannot be subpoenaed.
6. In short, whilst a potentially limitless personal tragedy is occurring in the lives of a growing number of entirely innocent people in this country, there is no way of stopping this happening within the law.