Reminder procedure and partial invoice payment

When I start the late payment dunning procedure, a list of late payment lines is generated. However, on my basis, the amounts due on this list do not take into account any partial payments made. For example, a customer has an invoice of € 2,500 due on January 10 (I configured level 1 after 5 days of delay) he paid me € 2,000 on January 12, when I start the procedure the amount due should be of € 500 and not the € 2,500 as they appear in the list. Did I forget to configure something?

There is not “partial payments” in Tryton but only pending payments.
So the report in account_dunning_letter display the pending payments so the customer has all the information about what is still due.
Also if you want to see the amount due, you must consult the “Receivable Today” on the party.

I understand, but the customer receiving this reminder may be confused by the amount :-). What do you think of subtracting the amount already paid (which can be found on the invoice) from this amount due?

If I’m not mistaken, the “Receivable Today” is all that is due, while I am talking about the remaining amount by invoice.

Well it is the customer on the first place that created such complicated situation.

It is complicated because you can have multiple dunning lines and multiple pending payments which can overlap etc.
Also using the payment_lines on the invoice to take decision does not seem to be really doable as it is done at the invoice level and not the move line. Also this is a link that could change at any time.
But maybe we should use the payment_amount of the module account_payment in case there is any pending payment but even here there are problems with the clearing move which will be included as pending payment and also deducted in the payment_amount.

Now we could add a total amount on the letter. In some way as all dunning are past, this total would represent the amount due today: Issue 10012: Add total amount on dunning - Tryton issue tracker