Default [Q] [HELP] Unlocking the bootloader on SCH-I535

I bought a Samsung Galaxy S3 SCH-I535 Verizon last year when I was traveling through US. I was able to root and unlock it to work with a carrier of my country (Brazil), I was even capable to set my language on the phone through the app "Language Enabler". I upgraded to android 4.3 and it worked just fine, but since when I upgraded the android to 4.4.2 my phone came back to the original language (english) and I couldn't set to my language anymore (Seems like Samsung is not providing additional languages outside US on this new android version) . Reading some treads here, I discovered that downgrading the android to a previous version (that included portuguese as a language option) would be impossible thanks to the bootloader. My question is, there is a method of unlocking the bootloader safely, so can I downgrade my phone from 4.4.2 to 4.3? Can anyone help me through it?