Unexpected R4k debit order due to Vitality's error

After signing up with Vitality in September 2013, I have only been debited for my discovery Health payment thinking this was included in my total debit order each month because it only ever comes off as one payment from your account.<br> <br> On the 1st of July 2015, I received a payment notification of an extra R 4 000 from my usual Discovery debit order. After phoning them up and Vitality openly admitting that there has been a systems error on their behalf, and certain customers have been neglected of being charged their monthly Vitality payment SINCE 2013! They have decided to deduct a huge lump sum of the accumulated monthly charges of the last 20 months into one payment to correct their system errors. No notice or warning, or simple sign of courtesy to the customer was given before this payment was made. <br> <br> How is this the customers problem, when Vitality is openly admitting to this problem being caused by a fault in their payment systems since 2013?? <div><br></div><div><em>(Supplier name changed from Discovery Vitality &amp