AT&T unlock code incorrect
I'm not AT&T customer (I use AT&T MVNO), and I got an AT&T Samsung A52 5G on eBay. I tried to unlock it through AT&T online portal, but it was telling me that they can't unlock it because it is active on somebody else account. I have no idea who is the previous account holder, the eBay reseller doesn't know either, so I have no way of reaching him or her.
I called AT&T customer service and they gave me an unlock code. I tried to enter it on the phone twice and both times got a message "incorrect network unlock code entered".
I called AT&T 3 more times to verify if I got the code wrong and talked to 3 different people, but they all were giving me runarounds about how they can't unlock phones on a call, that I'm not AT&T customer, etc.
I paid 30 bucks to an online unlocking company, and they gave me the same code as AT&T that still doesn't work.
What do I do, and how do I get a correct code??? Thanks!