Firmware is like software for your receiver. It's flashed to an eprom (Erasable Programmable Read Only Memory). At the moment, your eurovox won't descramble premium channels because it's illegal to sell a box that does this; it's currently a FTA (free to air) box, i.e. freeview. You will need to change the firmware on the box so that it wil descrable the other channels.
Here is the new firmware...
Digital Kaos - Downloads - Eurovox EX1000 SL Firmware
You will need a null modem cable and a PC with a com port to be able to transfer the firmware. Thare are guides in the download section that detail how to do this.