Unauthorized Billing

I signed up for a free 4 weeks course that I was offered by Vodacom Shake Promotion. I didn't even utilise the program. After 2 months Shaw Academy has made a huge billing on my Bank account that I didn't even authorise. E emailing them is just useless. They are a bunch of *****'s from what I have gathered from the reviews I have seen, I wish I never fell for the free course lies in the 1st place, would feel much better if I benefitted something from them but ive lost my money for nothing