the best way to unlock your Blackberry is to buy unlock codes from a trusted vendor.
Search internet for mobile phone unlocking websites. You will come across a thousand websites who can do this. Choose which ever you like. Do look for price comparisons and the unlocking instructions.
Recheck the Model number- Network to which your phone is locked to and the IMEI number before placing an order. If you made any mistakes in these details these people will never give you a refund!!
One more thing, before placing an order ask them about the conditions for getting a full refund in the case of a code failure! Think and make a wise decision.
I have personally bought the code for my Blackberry Pearl from unlockgenie.com. It is because they have good reviews on most of the mobile phone forums. I got my phone unlocked successfully from that website. I think their codes don't fail. The web link for the above mentioned web site is http://unlockgenie.com/