Fnb gave me a overdraft and I did not even had a j

As soon as I was fired from my job I took my letter to FNB bronkhorspruit branch. I wanted to make arrangements for my personal loan. The person took my letter and made copies. She said she would sent it to the right appartment. However that did not help one bit, fnb kept on taking the money so I dont think she did her job. Then she offered us an overdraft on our account which I assume she new we would not be able to pay as we gave her the letter that I lost my job. She told us that, that would not be a problem as fnb will only be taking R85 per month until we can start paying it back. Also we can pay it back as we see fit. Now fnb just take money from our account. They cannot even tell us over the phone why. As far as I know you are not supposed to lend any money if it is not affordable to the client.