Many banks have Online Bank Transfer as an internet payment mechanism. I have come across examples in Canada (Certapay), Netherlands (Ideal/RaboBank Debit Betalen), NACHA (www.project-action.org)

In this scenario the internet merchant transfers the buyer to his/her online banking portal to complete the payment process. The bank performs appropriate authentication further to which the transaction takes place. After this the buyer is redirected to the merchant site to complete the purchase process.

I would like to know what are the measures such payment schemes take in cases where there is a failure during the redirection back to the merchant after completion of transaction at the bank?
Is there some sort of transaction confirmation message/separate offline settlement process that the banks expect before the buyer account is charged ?