Fnb takes more than just their monthly bank charges

I am on a current account, and a debit order that I previously cancelled went thru of R7349,81 I didn’t have that kind of money in my account but it went thru and put me on a negetive balance mind you I’m not on overdraft the next thing I see a transaction from fnb of items paid no funds 6 they deducted R650, I logged a complaint the R7349,81 was reversed but the consultant said they will investigate the R650 . Against this morning on the 19/01/24 when I wake up items no fund paid R290 taken mind you I had moved money out of my savings to clear that R650 negetive balance and now I had money in my account so which items is fnb paying. This is not the 1st time this bank does this to me I’ve been quiet but I’ve had enough. I want my money and out of this bank that exploits people