Solution : https://service.sap.com/sap/support/notes/118295 (SAP Service marketplace login required)
Key words : 
customizing 'change view, additional key words, billing types faz, document types, payment request, payment clearing, program error, advance corrections, cancellation, prerequisites
Related Notes : 
       
| 113347 | Down payment process. as of Release 4.0x (standard) |