Is there a question in there or are you just venting?
As discussed in other threads, Jayco reserves the right to substitute equipment as they see fit. You might be able to get traction if the sales sticker explicitly lists 4 steps, and you lawyer up, otherwise I wouldn't hold my breath. If you wanna go for the long haul, knock yourself out but probably easier to do it yourself and sell the 3-steps to make up the difference. Maybe you'll get lucky and you find some who wants to trade. Or make a little wooden box to go at the bottom as an intermediate step.
"You don't get to judge me for how I fix what you break."
2018 Eagle HT 28.5 RSTS/2004 Chevy 2500HD 6.0 MANUAL