If extreme Promotion is Advocacy what do you call an extreme Detractor .. a Protestor ? a Militant ?

We have been working with a client that has been measuring customer satisfaction and relationship perceptions for 8 years.

They recognize that NPS as a “score’ does not really help with driving specific actions but it is highly informative and most importantly provides a rallying point everyone can understand, especially for the senior executives who provide funding and allocate resources to the CX program.

They are working to bring even deeper understanding to their relationships and so have been taking a hard look at their CX metrics architecture with two initiatives.

1. Recasting the relationship between their CX metrics and business metrics such as operational and financial metrics.
2. Bringing more color to their NPS scale by giving names to different levels of promoter and detractor.

What do you call extreme Detractors ?