******** DEBIT ORDER AUTHORISATION

I received an sms yesterday afternoon from my bank FNB stating that an eft payment of R 500 has been collected. I queried this with the bank as I did not make any transactions to this effect. I followed it up on my bank statement and the reference was listed as residuals ***. I was then advised to contact the residual department on *** and cannot get through. I was advised that the reason for the debit was a loan deduction as I have an outstanding loan with FNB. Due to unforeseen financial circumstances, the loan fell into arrears and was handed over to Unilaw (Pty) Ltd , a debt collection company with whom I have made arrangements and keep up with these arrangements. I initially paid an amount of R 1000 per month but I am currently earning a salary of more than half less of what I use to earn. I then arranged with Unilaw to reduce the payment to R500 and have been in keeping with the payment arrangement which payment is made directly into their account. What I fail to understand is how my account can be debited without my permission. This is ******** and goes against the FSB'S policy on treating Customers fairly .Taking away my fuel money to get to work!!