Who I have the same questioned this topic

I've had 4 service reps tell me 4 different things. No matter what I do even if selecting full price it always tells me to select a new data plan. I just want to deactivate my phone and activate a new one - No matter where I try to buy a phone from here, apple, or best buy everyone says I can keep the same plan, but tells me to add data.  Well my 'plan' includes unlimited data, it is not an add on or an extra. So why can't I just buy a phone for full price and activate it?