Hello, the code looks that is should work, only - append AND WAIT parameter to the COMMIT WORK to be sure the vendor is fully saved before we continue.
To you problem, I would probably keep trying to use VMD_EI_API_EXTRACT=>GET_DATA method because it just should work. Please try to create a vendor by hand (XK01) and assign some IBANS to him by hand, to be sure the creation was correct. Then try to read this manually created vendor by VMD_EI_API_EXTRACT=>GET_DATA, in the case the IBANS are still not filled, you probably should visit SAP notes library as I have suggested above...
Br
Bohuslav