Unfortunately 'they have no record' of the price, so they're billing everybody the full price. So even if you printed off the confirmation page, you're still probably going to be SOL. In addition, none CSRs I spoke to had any clue about this issue.
So tl;dr is Verizon doesn't care, they're going to take your money and there's nothing you can do about it. As is standard procedure for VZ.