PHONE UPGRADE NEVER WORKS

I have paid off both phones on my account for years now and it tells me the same thing that i have TOO MANY DEVICES ON PAYMENT PLAN, why are you telling us we have upgrades only to deny them and then not help?  I have tried so many times and i am sure others have been through this as well.. it tells us HAVE TO PAY IN FULL no matter what and the whole over lines for dpp.  if this can finally get resolved it would be nice after 8 years or more..