Default I9300 Sim Locked After Manual Upgrade

Hi guys, I am newbie @ xda. I am having trouble with my I9300 and I could not find something useful on internet since months.

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.

Thanks

Note: I manually upgrade to 4.3 but it locked again and I took it to technician, he downgrade and unlocked it same way.