Who I have the same questioned this topic

I bought my wife an iPhone in 2020. On the advice of the sales rep. For the iPhone early upgrade program. (Pay 50% you get to upgrade) but now they are saying the phone is too old. I can’t trade it in I have had Verizon for years. Never have had any problems. But this really angry me off . Who can I talk to about this ? What steps do I need to take to get what I was sold.