FNB taking unauthorised debits

my account has been debited and FNB has gone and put the money back but charged him R75-R100 every time for the debit orders being sent back and thus putting his account in the negative balance. I went to FNB this morning at the East Rand Mall and all I was told was sorry but the payments that FNB took cannot be paid back even though I pay monthly bank charges. They couldn't even say why in the beginning I am being charged. I had sufficient funds for my debit orders but due to FNB taking off transfer fees for cancelling the debit orders he is the negative. This affects my wife as well as those debit orders are for me as well. This has put strain on our household and we feel like FNB has literally ****** money from us. I feel they should reimburse my husband the money so that he can pay my accounts and not be in debt. They had no right to put the money back in for the debit orders and then charge him for it. Also they keep taking off his debit orders after the first whereas he has set it for the first of every month.