cannot return un-authorised debit

On 13/2/2016 First Auto debited my company bank account with R12676.42 claiming that ********** transactions had occurred on a Wesbank fleet card.<br> I instructed FNB to return this debit as \un-authorised\". They came back to say that they cannot return a debit from their \"sister\" company!<br> I find this totally un acceptable as its my account, my money & who gives anyone the right to just take money out of my account!!<br> Does this mean that FNB or its subsidaries can do just what they like with their customers bank accounts!!???<br> If First Auto have proof of ***** why don't they open a case??<br> My card transactions are processed through an FNB EFT system & each transaction has an authority number for that transaction - so if the F/Auto customer reported the card ****** why was it not blocked as \"hot card\" on the system - how can I be expected to loose R12676.42 for their (F/Auto) incompetence or their assumptions!!!??<br> I want my money put back or should I open a case of theft???"