FNB Sledgehammer Penalty for missed Debit Order

My small start-up business is struggling financially and I so happened to miss 2 debit orders to my surprise, I got charged R155 per missed debit order by FNB driving the business account to -R310. Two days go by and I still haven't deposited cash to fix my negative balance and I get charged yet another time for a negative balance (BIS/INT 2 ON TRUE TIERING). At this rate, by Friday I should be on -R1000. Is this regular banks' practice? Are there banks that are small business friendly as this sledgehammer approach is undoubtedly detrimental to small business operations?