EIP Return

I got an iPhone 14 Pro Max a few months ago on EIP. It was supposed to be jump on demand but for some reason it's just a regular installment. Idk how that happened because I was on the phone with an employee who must have done it wrong? Never had that problem before. Anyway, I'm switching all of my stuff to android, so I'd like to switch phone obviously. I've been told I can't return the phone to cease payments, but since someone internally messed up how the device was purchased, I can't even trade it in to switch. Has anyone had this issue and/or does anyone know how to fix it? I don't want to pay the $800 something I have left for a phone I'm not going to use just because someone internally messed up the process.