We are using Sage X3 V11 Pu6 - coordinating upgrade to v12 at present

In Australia our Vendors can be paid by multiple payment methods in particular 

- BPAY

- EFT

For some banks the BPAY file is prepared as a .CSV and the  EFT file is produced as a .aba.  Thus we have multiple file formats.

On the bank we have populated the file extension (we cant leave this blank) as aba

Now we want aba for EFT and csv for BPAY but all files are downloading as the file extension on the bank.  The system should be using the bank file definition I would have thought, why is it defaulting to the bank?

Has anyone else configured their system to allow this?