ufo. I bow to jon's greater knowledge of the labour courts,
I've never done one myself (but I was once threatened with one) however as far as I know, it's more an office where you file a complaint than a courtroom.
I suppose it all depends on a. how much money is involved, b. how much the OP needs that money, and c. if there's a point of principle involved.
inform the employer that she is breaking employment law by not paying you, and initially threatening legal action.
This make a lot of sense as the first (and ideally only) step.