Boycott all the businesses directly owned in part by the NUM - i.e. Primedia (702, Cape Talk, EWN, 94.7 and KFM), Tracker, Metrofile, Vox, Emperor's Palace, Firstrand...
These are not passive shareholdings via equity funds, these are companies that have significant direct ownership by the union.
Yes, that's right, the NUM directly owns significant stakes in a slew of "for profit", capitalist enterprises via the Mineworker's Investment Trust which in turn owns the Mineworker's Investment Company which has direct stakes in these businesses. These companies must be shamed publicly and called out for their hypocrisy - e.g. EWN running articles condemning the situation at Eskom, meanwhile their biggest shareholders are the cause.