Unauthorised debit order

I have an unauthorised debit order that cannot be disputed running from my account from the past couple of months. The *****s department is unwilling to assist to investigate and stop these transactions. I have been sent from pillar to post due to gross incompetence. The POPI act will be in effect soon but it seems our records are not safe with FNB. The debit order is for R631.94 with reference INUCOLLECTUC***0419