Transaction not appearing on my statement

There is something that has been puzzling. I made a payment to UNISA on the 28th of July for registration through EFT.Ok I began to wonder why my registration was not activated,I was then told they haven't received the payment. I then ask a Nedbank agent to retrieve the transaction statement for me so I can forward it to UNISA,guess what,the transaction is not on my bank statement.He then referred me to a Nedbank branch and I went there but the consultant just printed out my statement but the transaction wasn't even there and she couldn't explain to me why it wasn't appearing on the statement while I had recieved an sms showing that money was taken from my account. I'm so disappointed because now I couldn't register and nobody can explain what happened to my money