UNAUTHORISED DEBIT ORDER????

Who the hell are these people? What they R doing is ******* i was surprised by a debit order on the 26th october which I never authorised. Legal action should be taken against these people because I have never even heard of this company till yesterday when I checked my statement after noticing discrepancy with my available balance and to show that these damn people do not in anyway have authority to my account they debited my account on the 26th whereas I know all my authorised debits go through on the last day of every month for over 4 years now & without fail because that is always my agreed date since it is when I get my salary. Im fuming and i want these people brought to justice because even the lady I spoke to by the name of mellisa at SA Unathi on this number *** which was at 15:05 on the 27th was unprofessional and rude. What is my best way forward? Because I work hard for my money and to have this unknown company<br> just take my money and misuse my account without my knowledge is unfair and downright ********. Below I provided the ref provided by sagepay when I did investigation as to who these people are.<br>