How to Exclude prepaid transactions from Dunning letters

I have a request from our Business to Exclude transactions considered as prepaid. So they have been paid in advance and the transaction has a due date the same as the transaction date and also have a specific payment terms ID.

I can isolate the specific Payment terms ID and exclude it in the Data Model, however for a Customer that has only 2 of these 'prepaid' transactions in the Collections module it shows them as delinquent it still generated a Dunning letter but the table was blank and still attached 2 copy invoices.

We don't want to send a letter for anything that is prepaid as they do not need to be collected on they've already been paid but may still be 'open' and not yet had the payment applied to it.