FNB Charged me R465 penalties for going R206 beyond overdraft for one morning!

I drove back from Durban, car broke down, used my available balance to tow my car, two days later the toll fees come off my business card and put me beyond overdraft, which I rectified with a transfer right away. FNB charged me R155 penalty fees for each of 3 toll fees that came off! I was beyond my limit once for one morning by only R206, phoning to complain got me nowhere, yet I get charged R465 penalty fees!?