Unauthorised Debit in a different Bank Account

Over the holidays i experienced a problem with my son losing his prosthetic eye and i had to put some money together to get him a new one. I was forced to reverse my debit orders in the arranged bank account which i have NEVER done before!! I have had a loan with capitec for almost a year and i have been paying them loyally. I then had R700 deposited into my Capitec for food by a friend which is not where the debit orders go off. Capitec bank then went and debited from that unauthorised bank account and left without food for me and my family for the rest of this month. i called Capitec to find out why they did that and Thokozani Langa of Capitec informed me that they had every right to fish in all my accounts and retrieve what ever they could and there is nothing i could do. Is that really legal? I am pleading with Capitec to please return my money if they have any empathy in them.