Unlocked phone not unlocked

My Verizon TCL 10 5G UW phone that I bought previously owned is unlocked. Verizon told me it was and should be good to go on any other network. However, that's not the case. I insert any other carrier SIM and after a brief period of actually working properly (about 1-5 minutes), it says it cannot be activated on another carrier at this time and to contact Verizon. They won't help because I'm not a customer of Verizon. The closest i came to anything was being told that even though the terms were satisfied and the phone was indeed unlocked, it was still attached to a disconnected account and needed to be unattached. I have no way of contacting the original purchaser and i knew this before hand and called Verizon to make sure it was indeed unlocked and was told it was and no fraud, payments owed, blacklist or anything was wrong and that i should be able to use it on any carrier so I bought the phone. Not i can't use it because supposedly it needs unattached front a disconnected account. What to do?

Re: Unlocked phone not unlocked
Customer Service Rep

I am sorry for the issues you're having with the device not being able to use it as you mentioned in your explaination, tomhaskell38. Let me get some more details about the concern to see if we have any available options. What is the IMEI of the device? To confirm, were you the device was on an account that you did not have access to? Please send us a private message with this information so we can take a look into it further.