Unauthorized debits orders from Nedbank #********

I'm a Nedbank account holder, for the past three months I've been struggling with companies debiting my account without my authorization, every month I have to go and ask for them to reverse the unauthorized debits but they fail and tell that they can only Stop them but again my account was debited and those debits are not reversable I think Nedbank is part of this **** because people can fiddle with one's Account. I'm really not happy with this kind of service because my money is safe at all.