i want my money back

On the 15/12/2015 my current account was debited twice with R550 and R1732.62 both these where debited to my personal loan account.we had an arragement of R550 which they needed to debit from my acc,on the 15/12/15 i called and spoke to a lady by the name of Zanele she promised me that yes its their fault to deduct twice.she then promise that the money will b refunded to my account 3-7 days..since then i have not received my refund. When i call today they tell me the money cant be refunded and i dnt knw why.i want my money nedbank.i have two refunds that needs to be given back. Iv had enough with this bank.i have been complaining and nothing happens,im leaving this bank and i want my money ,i want my money..im really tired to complain each week about the same company.im so fed up now.how am i gng to survive if they keep on taking my money.im done with this bank.im tired now