Cancellation of a contract

Sometime last year one of Body Lab's consultant ******* my fiance to enter into a contract with them, she was told that they wont debit her account until she comes to their offices and activate her membership, but to our surprise comes month end they debited her account. I tried to call them about this matter trying to understand how could they enter into such a contract with someone who is unemployed but they didn't show any interest in helping me but instead they keep intimidating me that is either she pays the money or they will blacklist her. As I am speaking now the balance is over R 2000-00. May please be assisted so that the membership could be cancelled.