https://forum.howtoforge.com/threads/billing-module-ispconfig-profoma.68140/
Billing Module ISPConfig profoma | Howtoforge - Linux Howtos and Tutorials
If i have a Proforma invoice and i want to convert it to an invoice, the proforma invoice isn't removed. So i end up with an invoice and a Proforma...
billing moduleispconfighowtoforgelinuxhowtos