My I9300 was factory unlocked. I made a mistake while manual upgrading, I install Spain-Movistar sim locked 4.1.2 on my phone. After it my phone became simlocked. I could not solve this problem and I took it to a technician and I paid him. He does not say what he done on my phone and he unlocked it.
Now it is running rooted 4.1.2. He can not upgrade the phone to 4.3 because he can not unlock it.
Please help me I want my unlocked phone again and I want to upgrade it manually in future.
Note: I manually upgrade to 4.3 but it locked again and I took it to technician, he downgrade and unlocked it same way.