Bad service

I have full signing powers on my children's accounts for the reason that they are not in the country . They hired a car in Swartkopmund and the amount was deducted from their balance on pre authorization ,when they took the car back the authorization was cancelled by the rental company , but the pre authorization did not reverse , so the amount is not back on their balance - this happened on the 17th of May - since then I have been phoning the call centres to get this rectified and have spent a lot if money on about 12 calls , without success - if it is not a robot , then I get shunted from one department to the other and one person says this and the next that . Eventually we even sent through a form to debit card disputes , only to be told it is the wrong department . This money is needed and help is just no where to be found !!! A robot also cannot solve these issues!!