cancelation fee

We met two men about 3 months ago at our Protea Glen mall in soweto. They canvassed us to join the gym where we will gym for free for 3 months. But in the end of March they deducted R637 from an acc that we wrote on the form for two people for which they told us the gym intial fee is R199. We decided to cancel the gym membership and they told us its R1472 to cancel. We refuse to pay this because we have never attendend this gym not even once