Hi,
Speaking from my own experience i used twice this service UnlockCode4u.com
http://www.unlockcode4u.com
I was also told by my network provider to wait for the code over 2 weeks and then again 10 days and finally i couldn't wait any longer, and i went online, i dont really trust to easy and it took me a while before i decided but after all it was worthy, i unlocked already my phone and then my wife S4 with no issues :-)
Hopefully that will help a bit!
Good Luck!