help.

[Cule12345]

i updated firmware on my galaxy s3 I9300 via samsung kies,and my sim network was locked,then i paid 20 dollars to some weird man to unlock it,and he did it,but he told me to never update my phone again because it will happen again. and now i see jelly bean is available in my country,so shoud i update my phone again?? sorry for bad english