Unpaid former employee

I am a former employee of Truworths Head Office in Cape Town i resigned because of a better job offer, my contract said 2 weeks notice. When i handed in my resignation letter they said is a months notice i will be penalized. i worked 3 weeks. Now mnthend they refused to pay my salary. They took it all saying i owe R2000 ontop of my salary. They helped me get a job Yes but i am unfairly treated. Everyone beware do not serve notice at that place. Take your salary on salary day and disappear. Most employees did it, i never understood why... now i know. How can a big company like that refuse to pay resigned employees. Even when i was working there, they refused to increase our money while we worked 12 hrs a day, 6days a week. 10days leave onces a year. I am talking about this company. I want my money.