Bank Reconcilliation question

How do I reconcile a day's banking when there has been a refund that day?  Also the refund in question may be from another day's sales.  Obviously the day's card sales don't match as the total is minus the refund, I know there is an option to add the refund but finding the initial sales to match is difficult and the refund option doesn't always work.  Any advice or help would be greatly appreciated