[madmadmax]

My carrier has installed custom firmware on my phone. How do I change to the default firmware? Also would it be a problem installing addition languages on a firmware only supporting English?

[JSanders]

What crappy firmware are you talking about?
Anything specific would be helpful.

[madmadmax]

My carriers logos showing up every sec, the BlackBerry OS is in Hebrew.

[dc/dc]

This is not a carrier issue, and is therefore in the wrong section. You cannot remove carrier logos as they are not associated with firmware, and your phone's OS is in Hebrew because your carrier is Israeli. You should, however, be able to change it to English or Arabic in your device's options.