APO DEDUCTION UNAUTHORIZED AND NOT WARNED PRIOR

I have seen an APO Deduction of R1330 from my Nedbank Cheque Card. I was not told anything prior and consequently I cannot take my child back to school. Meanwhile, Nedbank has frozen the use of my available balance in my Credit Card. The Money is available but the machine has been set to kick my Credit Card off whenever I try to use the card. I wish I get an explanation really. I appreciate the facility but to block everything like this while leaving a very small bank balance amounts to leaving my family in shambles. Can anyone explain. I did not know of this APO Deduction prior and hence did not expect it. Kindly assist. To add trouble such a deduction is irreversible and I have to call Nedbank when it is closed on a Sunday.