You can get it unlocked at 数码广场, aka computer city, on the northeast corner of the intersection of RenMin NanLu and First ring road. The shop that I went to is on the first floor, in the corner- it is an apple brand shop- but there are places throughout the complex that should be able to help you out. You will probably have to pay around 100 kuai, though you may be able to get it cheaper if you are a canny bargainer. If you are a DIY type, you can also download various programs online – many are free- and use them to unlock your device. These include QuickPwn, RedSnow, and a bunch of others. The only potential difficulty is that you have to have the right program for the operating system of your iphone, and there are various versions.