DEBIT ORDER DEDUCTED WITH ARRANGEMENT IN PLACE!!!

I am currently unemployed and stated to Nedbank that i am seeking employment and made aarangments with them to debit R500 per month of my account as i am doing photography work freelance just to make ends meat but Nedbank has taken R4833 off my account that is a my daily bread and fuel and rent and now i am trying to get the refund by reversing the order through fnb but they have locked the account and i cannot get the money back and it is now left me poor for the next few weeks and behind on rent and food,i cant understand why they would do such act even when a agreement was made...i request that the refund be done as promised and the arrangement i will keep till i find employment!