Unfair erro

On the 30th of June 2018 I was expecting a payment of R3800 to be deposited on my Old Mutual Account then on the 01 July 2018 I received an sms notification from my Phone advising 3800 was deposited on my account, I went to draw the R2600 then transferred R1000 to my savings account but I noticed that after a few day money started disappearing on my account I could not go to the branch as I am working in Pretoria and knocking of late I work from Monday Saturday...... Then my salary was deposited on the 26th July then R2900 was talent from my Acc..... I went to the bank on 28th of July to log a query at the branch. The consultant called the customer care line and were informed that the bank is a aware of such a thing as other customers have been complaining about the same thing and their IT department is looking into the matter. The next thing I was told was that they can't refund the money. I feel I was treated unfairly as they just too my money without making me aware and the worst part about this is that I have debit orders on my account which are going to bounce due to this inconvenience......now I have to suffer Due to Old Mutuals incompitency..... My account is a savings account not a cheque they even told me that the bank did an overdraft on my account I was not even notified when the money was taken is this allowed. ????