Authorize.net waits until midnight every day to submit transactions to the banks, even if the gateway is set to auth+capture. Before midnight, the status of the transaction is 'Unsettled'. After it is submitted to the bank at midnight, the status then changes to 'Settled'. They do not allow the refund button in WHMCS or other carts to be used for unsettled transactions. They have a different function to VOID unsettled transactions. A button for this in WHMCS would be helpful to cancel suspicious transactions before they are submitted to the bank.