I think they would charge you possibly?
This site will do it free but can take up to 14 days I think:
http://www.unlockblackberryfree.co.uk/
Just follow the steps, they're rather easy.
I have used them and it is free to unlock one Blackberry per email account if I remember correctly
You need an MEP code to unlock your phone
Watch this video i made on youtube. This will show you how to unlock it for free - http://www.youtube.com/watch?v=T3azXBzat8Q