Horrible mobile service

In Feb. 2024 we received an email about shipping out a galaxy z fold 5 that we didn't order and a charge of $215.  We called and they said no problem, that they would try to get it canceled but if not, to just not accept the package and it would get shipped back to them.  The phone did ship out but was intercepted part way and sent back to their warehouse.  They had refunded the $215 but continued to charge us a 79.99 device fee every month.  I didn't catch it right away because my husband handles that account.  By the time I noticed we had incurred several overdraft charges and when checking the account, it shows we had a z fold 5 in our possession and a z fold 4.  Now my phone is the z fold 4, but it had been paid off since Nov. 2023.  So my account now shows that I have 18 months of payments remaining on a device that I've had paid off since Nov 2023 and 23 months remaining on a device they have in their warehouse.  We called several times repeating the story over and over again like they had never heard it before.  We were refunded the 79.99 each month (supposedly) and I was told we would not have a payment due until August in the amount of $49.  So when we get an email that our account is past due by $136, we were like what??!!  And that my next bill still shows a device payment.  So after another 2+ hrs on the phone with them, I'm like just get this corrected and my phone unlocked (like it was in Nov. 2023) so I can take my service elsewhere.  Then they want to say they won't remove the false account of 18 months remaining on the phone until the overdue amount is paid.  That's illegal, you can't just lock and unlock and add and subtract months still owed on someone's account just because you feel like it....and nobody is located in the US that you speak to.  I will be shouting it from every platform not to use these people...