Gym take money from my account without consent when the contract not even in my name

My son took out a contract with the Alberton branch. They have the audacity to debit my bank account after two years and without my signature or consent. This is unacceptable and appaling and upon contacting them they informed me they cannot cancel or refund me and they hold me liable for the outstanding amount of R7000. I am unemployed and under administration and know full well that i may not enter into any contract or agreement. This gym just wants to take money and don't care where from or about your position