Nedbank breaking agreements again!

I was recently retrenched and asked Nedbank for a payment arrangement on my personal loan (16/01/15). They agreed to a 50% payment amount for 3 months (confirmed 17/01/15 via sms ref no. ***) But they still debited the full amount, not only once, but twice. They even had the gumption to send me a confirmation sms the second time (27/01/15 stating the same ref no: ***). The relevant consultant (Nash) assured me I would be refunded, but nothing has happened. Apart from this, I was paying in arrears - as per the initial agreement, now I am paying in advance - basically within two weeks I had been debited twice at the full amount. When trying to enquire/speak to the consultant on ***, I am either cut off (3 or 4 times) or kept on hold for over an hour each time. I have called on a number of occasions to try and sort this out. This is not the first time Nedbank had either debited me on dates without my consent, but has also charged me fees which I had to fight to get back.