Unlock my Samsung Galaxy Express Prime 3 - AT&T PREPAID
I bought my Samsung Galaxy J3 2018 Model No. SM-J337A in September 2018. I used it for a month with AT&T prepaid network and switched to H2O prepaid for a couple of months. I never used the phone again after that.
I now want to use the phone in another country and tried to unlock the phone by going to att.com/unlockdevice. After going through the process I received an email that said, "Before you can unlock this device, the owner must remove it from their account." Since it has been 3 years since I had a prepaid account with AT&T, customer service can no longer find my account but the phone is still connected to that old account.
How can I get my phone disconnected from my old account and unlocked? I still have the original order number when I ordered the phone online at att.com.