Nedbank has no security. What do I pay them for?

I made purchases online and money was allowed to be deducted from my account without my authentication. The amounts that was allowed to be deducted was not the same as the amounts that I authenticated via the Nedbank app. There was a R20, 000 discrepancy.

I want to know why there is an authorization process? Surely this is there to orotect the client and his money. In my case it did not protect me or my account in any way what so ever.