How did this happen?

Last week the 31st of July someone/place named Digicash \debited"money from my STD Bank Check account. Last time I checked you had to sign documents to authorize a debit from your account. Yet this happened. It makes me very scared to think that my hard earned money can just be taken from me like that. I trust std bank to keep my money safe? I can understand a normal transaction but a debit? Isnt there staff that check that forms are filled in and that there are procedures followed and then THEY load the debit?? Was this an inside Job? Something went terribly wrong here"