NMC protecting its members from complaints

I have heard disturbing reports of the Nursing and Midwifery Council (NMC) protecting its members from complaints. One member of the NMC has been threatening people on Twitter, actions that are surely incompatible with their position. Worse of all, when complaints have been made about this person, the NMC have claimed that they cannot investigate without the individual's PIN. It seems quite inconceivable that the person involved can avoid NMC investigation because the complainant does not know what her PIN is. It smacks of the sort of cronyism that ought to have been eradicated from professional regulatory bodies in the last century.