Samsung KIES is not the only way to get official Samsung Galaxy S III GT-I9300 firmware. You can use Check Fus Downloader to check for latest official Samsung Galaxy S3 firmware upgrade. And even download it and install with Odin manually later. Or you can find them at XDA Forum and SamMobile website too. With Samsung Galaxy S3 unlocked bootloader, you can try other region firmware too. For example, my Samsung Galaxy S3 is Malaysia unit and loaded with South East Asia firmware. I can install UK I9300 firmware on my Malaysia SGS3 since international SGS3 hardware is the same. So no need to wait on your region firmware for long time and try other region latest firmware first. Europe region always get the latest firmware first. And Malaysia will get it several months later…
UBALE6, XXALE8, XXALE9, XXALEF, ZSALED, BVALE4, XXALF2, XXALF6, XXBLFB, XXBLG6, XXBLG8 and XXBLH1 are the current official Samsung Galaxy S3 stock firmwares available to download at XDA Forum. And there are carrier branded Samsung Galaxy S3 firmware to download too. By the way, be sure to download your current official Samsung Galaxy S3 stock firmware and store locally. You might need it when need to send back for warranty claim. Oh, can’t wait for Android 4.1 / 5.0 Jelly Bean firmware to come…
Installation guide ~ How to install firmware on Samsung Galaxy S3 with Odin? (Video)
Download official Samsung Galaxy S3 firmware and stock kernel here, here or here.