Check your AC Brabys Statement debited me with Someone elses Account

Please check your statments if you have an account with AC Brabys . We only signed one debit order for our account but was debited with someone elses account for over 10 months. After querying what the second debit order was for I was told that we had been debited with someone elses account. Upon requesting as to how they had gained access to the second debit order no answer was given. They then apologized but questioned me as to why it took me so long to inquire as to why there were 2 debit orders coming off our account. If I had not brought it to their attention I will still be paying someone elses account. They only refunded me the debit but not the bank fees,