Why my Moto X won't unlock from AT&T with provided codes?

[Melissa Ellen]

Just like many other posters, I have a Moto X 1st generation locked to AT&T which has been impossible to unlock for over a year. The difference in this case is that I've had 2 unlock codes, provided by AT&T on phone which have not worked, giving the same message as it ever did (after any random numbers or tried codes): "network unlock request unsuccessful". I am now searching for unnoficial alternatives, as I believe my phone might be defective. Any alternative or enlightment on what I might have done wrong would be deeply appreciated.

 

[Melissa Ellen]

P.S.: I am not the original owner of the phone. It was bought by my aunt in USA and months later given to me, then I brought it to Brazil. Also, AT&T provided me 2 different codes on a span of 2-3 months.