FNB IS ALLOWING TRANSACTIONS TO GO OFF MY ACCOUNT EVEN THOUGH I DO NOT HAVE AN OVERDRAFT ETC

Logged into my Bank this morning and my account is -R1721 ***. Something Went off on my account for -1,461.48 and then you guys charge me R200 FOR no available funds . I do not have any debit orders for that AMOUNT and it is stating NETCASH Capetown i live in JHB. I do not have Online purchases limits set on my card as my card is not working for almost a month and a half because my card did not work ,i do not have an overdraft with FNB so how can you guys allow my account to go into a minus with so much money it is suppose to bounce I want this investigate as i did not have funds in my account for since last month pay day . *** is this. I want this charges reversed or i will take this to the ombudsman for ***** and FNB is allowing it.