Bank charges more but doesn't pay off my debit orders

I had a issue with my cellphone contract which led to my balance being negative for a day, in that day, the bank charged me R500 for the negative balance and I ended up even for negative. That was fine as I funded my account. There were additional charges of R350 and R110 after that, and yesterday I found out that one of my debit order were not paid, even after I funded my account. How did that happen? Truly terrible bank