Answer:
Wildcat strike
Explanation: in this type of service, workers goes on compulsory strike themselves without informing the union they belong or the body responsible for their welfare.wildcat strike usually hinder or downgrade (undermine) the position of the union. Workers usually stop working so as to enable in protest until their voice is heard.this downgrade the office of the trade union and makes them seems powerless before the eyes of the public that they can't control their workers and they are not unified because the strike was not sanction or approved by the union.