LG Velvet is on Mint network but AT&T has it labled locked
My LG Velvet was purchased unlocked. Mint Mobile had it on their network for over 6 months, Suddenly I could not receive calls and my internet was slow. After numerous call to Mint they tell me that my phone is locked by AT&T. This phone has never been on the AT&T network and was working fine for 6 months. Tried talking to AT&T to work it this out and got nowhere. Mint Mobile can't do anything . Tried using one of the unlock services , paid $24,95 and did nothing to unlock it.
Any suggestion on how to get the locked status off this phone