Disappointment... FNB do better and please give me proper answers

A bit of a confusing story but I will try and keep to the point.

On the 28th of December I paid my vodacom account and got the confirmation email from FNB. On the same day I bought dog food at an absolute pets close to me. Around the same time Woolies also deducted the amount I owe them from my acount.

Now the problem comes in that these amounts was only deducted off of my acount last night. At about 6 I still had about a thousand rand in my account. Woke up this morning to have my account in the negative for about 3000.

I don't understand how this is possible. They say that the vendors only banked on the 21st. This is the first time this has ever happened. How can three different vendors all at the same time only bank a month after I made payment? (The one, woolies, was debited from my account so it was their debit)

I have now had to transfer a substantial amount from my savings account... R5000 to be exact. to be left with R1900 because of these transactions. There is also an outstanding authorised amount of over a thousand rand showing that I have no idea what it's for.

FNB, this us completely unacceptable... HOW am I supposed to budget? And this at the end of January?