being held at ransom

So I have a Nedbank cheque account. In December I made a couple of transactions via Speed Point at different locations. I received SMS confirmation for each transaction as well as the latest balance on the account. <br> <br> The following day I withdrew the money that way left on the account ( according to the SMS notification) then about a week later I get a call from Nedbank claiming I owed them money for the transactions I had done the day before I withdrew what was left. I explained to the lady that I only took what was left after the transactions i.e if I had R2000 then swipe for R400 I'm left with R1600, right. So if I then take out that R1600 you can't say I still owe you the R400 which was allocated. <br> <br> To make things worse Nedbank fined me a penalty of R90 per transaction. I laid a complaint which no one seems to know about. Every time they call me. Now I'm getting threatening SMS about legal action yet my complaint has not been dealt with. <br> <br> I'm now considering complaining to the ombudsman and consumer council.