Unauthorised debit order

This company debit my account every week as agreed between us, recently they started debiting a monthly installment and still continue to debit the weekly instalments.Ive called the head office reversal times with no assistance.The sales representative is hanging up calls when I try to reach her for assistance.Her branch is in Elandsfontein Atlas Finance and goes by the name Vumile.Im not happy with the service I received , especially now that we facing a covid 19 crisis,money is needed,but I can't even buy simple essentials such as food,because last week my weekly salary was debited,this week they debited a weekly amount,which means I'm only left with money that is not even enough for rent and electricity.