Wordpay fraudulent activity

I would really like to know if any other opencart user has had problems with fraudulent orders using worldpay. We have discovered 7 fraudulent orders over the past couple of weeks and when we logged into the transactions on worldpay we discovered they were highlighted as having failed security checks in worldpay but they did not notify us to the goods were distributed (we are a furniture store so the goods are high cost). Can anyone offer any tips or advice on how we can prevent or easily identify these? Or even if they use another payment provider which has a good level of services for notifying re failed security checks.
Any help would be appreciated?
thx