Partial payments

Hi there,

This is the first month we have used essentials. I have looked through the other posts here regarding partial payments and I can't seem to find the answer to my issue. 

We often have clients part pay invoices due to the nature of our business. 

These part payments come in as part of a merchant summary from the bank so can't be changed. 

so...if a customer pays $125.00 from a $500 invoice and that partial payment comes in a merchant summary lump sum of $500 which is also for other customers how do I change the transaction so I can pay the $125.00 off the $500?

Hope that's clear. 

Jo