My wife bought me the same phone a couple of months ago and it was difficult to find someone to unlock it. Didnt fancy the on line ones as did not know how reliable they were.
I ended up going into bandit country (Tottenham) and a guy done it, while i waited, for a fiver. It was a small shop, not one of the big chains.
So find the worst area where you live and someone there should be able to help.