Standard Bank the **********

So a couple of years ago I had a Standard Bank personal load which was paid diligently every month via debit order. After a couple of years I was able to settle the account in full which I did. Me under the impression that the account is paid in full only to realise that they have been debiting my account every other month even though I have requested a stop order on it. Now going back I see it's a debit here every other month. Keep in mind the account no longer exists as it was paid up, confirmed in writing and everything. I want a refund and I want my refund now. Standard Bank has no authority to even debit my account.