Double Deduction of debit orders with no refund

I have two loans with nedbank which amounts to R6400 so on the 30 of October they debited double the amount and i called them immediately and requested a refund i was told their turn around of refunds is after 7 days and i explained to them that the money was for my children school fees and house hold purposes i called after seven days because the money was not paid in to my bank account i am taken from pillar to post my children did not pay school fees we dont food and electricity so basically nedbank is making my life a living hell .