Impossible to cancel contract or stop monthly debit order

Virgin Active continuously debited my bank account on the wrong dates which are not what I agreed to in my membership contract. This resulted in my bank charging me additional penalty fees for unpaid funds debited on those wrong dates. I had to go into my bank and speak to a branch manager to help me to force stop the debit order after several failed attempts to reach Virgin Active's accounts department. Nearly two years later and today, I receive an e-mail claiming that I am in arrears and need to make payment of nearly R6000. Which tells me their next step is to try and blacklist me? How can they only make contact with me now, after all this time, and claim I owe them money? Why did they not contact me after the first failed debit order triggered on their system to try to sort out this matter with me or to make a payment arrangement with me, their valued customer? This is ****************! I owe them *****! If anything, they owe me!