Gym Company review: Gym membership

Last November my friend and I were lured by this promoter at Maponya mall to sign this form. He said we weren't signing an official contract but a "pass" to allow us into the gym for free until December the 31st. He said we wouldn't have to pay anything unless we went to the gym and told them that we want to be official members and that we want a mebership card. However, on the 31st of December, we both had R300-and something debited from our accounts, what's even worse is that they said we'd only have to pay R200-and something *if* we wanted to continue with the membership and gave them consent to take money from our accounts. Now we're receiving calls and they're telling us we're gonna be blacklisted if we do not pay.