All unlock codes that we sell are 100% guaranteed to work. If a code for some reason does not work we will first verify that we sent you the correct code. If we verify that we sent you the correct code, we will ask you to send us a video of you unlocking the phone. That will show us if you are following the unlocking instructions correctly if you are and the code does not work we will just refund you. Please note that some IMEIs may return as Not Found from the server, that means that for some reason the IMEI does not exist on the server. In that case we will refund you. But again these are both very rare cases.