You can recreate a bank file for any batch of payments from the History area of the Transactions screen.
Locate the payment transactions by selecting the date range or by entering the range for the transaction numbers you wish to re-create the Online File for.
Select the payment transactions by ticking the box next to the entries.
Once all of the transactions have been selected click Re-create Online File. Select Direct Debits or Direct Payments depending on how you are paying. This will automatically take you to the Online File area where you can Generate your file as per normal.