I have a paid off phone but Verizon says I have to pay the full price of the phone to upgrade. What?

So I had to get a new phone when I joined Verizon back in April. Some water got into my old phone and rendered it unusable. I was originally on the plan by myself and later (approximately 6 months later) I added my husband. He has an iPhone 13 that barely stays charged for more than 3 hours. He came from his mom’s Verizon account and she has been a loyal customer for more than 10 years. On her plan, his phone was paid off 1 year ago. So naturally we wanted to upgrade his phone when he switched to my plan. Verizon said I have to wait 6 months for my spending limit to reset but it never has.. my trade in on my phone got me $800 off but yet I still can’t finance a phone for him. My credit score is decent and it’s $230/month just for us 2.. thinking about switching carriers because that sounds ridiculous. I would understand if we both (just for example) got brand new iPhones and the most expensive plan but we don’t..

Anyone else dealing with this?