How to calculate dunning charges depending on the height of the amount?

In the Netherlands we are used to charge customers for the costs of dunning letters. (and also post those charges!)

I don't see a standard process in PeopleSoft, but for now we use the overdue charges process to calculate fixed amounts for dunning costs.

The problem is that we are obliged (by law) to charge € 7 for items below € 500 and to charge € 15 for items >= € 500.

Our solution was to make two overdue charge ID's. One ID for all items (no exclusions) for € 7 and one ID for items >= € 500 (exlude all items smaller than € 500).

We also have configured to charge both ID's only once per item.