Help in flashing new firmware(R3EG004) for my W980

Hi all,
I downloaded a2uploader and followed a tutorial on how to flash my phone. However, I was stuck at the step whereby you have to search for the firmwares which must have mbn and fbn extensions. The closest I got to finding the firmware required was when I looked under the Downloads section of topsony.com but they were in the rar format. :(

So can someone please kindly point out where have I went wrong or inform we where I can find firmwares of the mbn and fbn format? Thanks a million!