Finance charges on A/R Invoices

We just upgraded to Vantage 5.1 with the understanding that the
finance charge function would be fully functional, but now we are
being told that it still doesn't work. We would appreciate any
advice on how anyone else is dealing with this problem. The only
solution I can think of is to create a report that calculates the
finance charges for each customer, and then manually create misc.
invoices for each customer. Is there an easier way? Thanks