Once a scammer has access to your account information, they can debit your account every month with your knowledge or approval. Scams can come in many forms, but all of them are designed to take your money. Overpayment scams are very popular on online auction sites, such as eBay. The buyer overpays for your item in an amount greater than what they owe.
Then they'll ask you to deposit the check and transfer the difference to them. These tried and tested services are good for sending funds to your loved ones. Bank transfers are often requested as part of sweepstakes and lottery scams, where you're asked to send money to help process big wins that never materialize. When a MoneyGram or Western Union transfer falls into the hands of a criminal, it's impossible to trace.
There are limited protections for this type of transfer. If you're ever asked to pay for a product or service by transferring money, consider it a warning sign. If you suspect that an email or phone call is coming from a scammer, Google the name of the company followed by “scam”.