Contract cancellation and handing over the contract to debt collectors

My name is Mercia I took up a virgin active contract by signing up via Facebook . They made contact and I engaged with the consultant telephonically . We met up at Westgate Trumps to sign my contract and gave me my bag which I paid for . I realised that the gym is far to travel that I was assigned to and I called him the next day the 15th of February to tell him to cancel and he agreed . I am being called daily by harassing debt collectors which I have being handed over too. They say I am owing them in the regions of R5K . I want to have clarity and understand how is this possible. I have never stepped foot in the gym and had I being made aware of the cancellation clause . I would have never taken the contract in the first place.