Negative Balance in Savings Account

On 07Sept2015 , an amount of +/- R1600 was deposited to me. I then withdrew R1000 on the 8th Sept 2015 at 15:04 an another R 600 @ 16:30 on the same day. There was a final balance of 12.30.<br> <br> I then left the country and did not use my bank card or bank account.<br> <br> I then returned on the 18th and received an overdrawn message on my cellphone and a balance of R-33.18. I deposited 20.00 into my account and again received the same balance of R-33.18. The deposit was made on the 21st Sept.<br> <br> First, I did not know that I could have a negative balance on a savings/Transacter account, second, why is there such a huge negative balance? Is this normal or is there something fishy happening at Nedbank.<br> <br> I would go to the branch, however they have proven *********** in previous matters.<br>