Pay what is due Car Service City Rivonia

This business operates like a fly by night,the manager at Car Service City Rivonia in De la ray street treats subcontractors like stupids,as a qualified auto electrician with 22 years experience,I got a call to come diagnose a car and after establishing the problem,charged my call out and was never paid and when I call to inquire was threatened by Richard only to find out I wasn't the only electrician to have suffered this,I don't think the owner knows and I suspect he is pocketing the money,I hope it backfires one of these days