Solution : https://service.sap.com/sap/support/notes/439493 (SAP Service marketplace login required)
Key words : 
system generates incorrect billing documents, sap applications whichgenerate billing documents, additional key words euro, attached source code corrections, general billing interface gn_invoice_create, general billing interface, volume-based rebate, object type vbrk, billing document currency &, agreement currency locked
Related Notes : 
       
| 437429 | Message SG105 List settlement documents, setting up incomes | 
| 358893 | Create billing document with different document currency | 
| 314121 | Expiring currencies in Release 3.1I to 4.6C and higher | 
| 183379 | Composite SAP note subsequent settlement (Purchasing) 4.6 | 
| 152725 | Collective note: Subsequent settlement (Purch.) Release 4.5 | 
| 104668 | Collective note: Subsequent settlement (Purch.) Release 4.0 | 
| 67481 | General billing document interface - collective note | 
| 40147 | Collective note: Subsequent settlement (Purch.) Release 3.0 |