Download iFile:
Start iFile, Then go to: /System/Library/Carrier Bundles/iPhone/YourCarrier/ and /signatures And rename all three "overrides_N51_N53.plist & .pri" files to "overrides_N51_N53.plist%".
Then go to /var/mobile/Library/Carrier Bundle.bundle (note the space there) Open carrier.plist and select property text viewer to open it Scroll down till you see Show3GSwitchOnCat10HW Flip the switch on the right from off to on Click on done Close iFile Reboot your iPhone
Now you should be able to see the 3G switch under Settings -> Cellular, Turn 3G off then you should connect to EDGE or GPRS.