We are selling Google Apps to clients (Reseller). At the beginning of each month, we are receiving an invoice from Google Cloud GSuite by email.
Inside there is a detailed list of rendered services:
Example: 
domain1.com    EUR 28,00
domain2.com    EUR  2.80
------------------------
total              30.80 
We want to push these details into our billing system to create invoices for our customers.
I already had a look at various google APIs but none of them seems to fit the bill (pun intended).
I'm looking for the right google API endpoint to talk to.