Upgrade/Replacement-Verizon help

I have 4 cell phones on verizon for my family (customers for many years). My daughter's line isn't up for an upgrade till May 2013. She initially had a Droid which was a dud, so I picked up early this year an iPHone 4 on ebay. I would love to get the iPhone 5 now for her (2yr contract extension is fine), but Verizon is saying that since the phone is so hot, they can't do it. This doesn't seem to make sense since if I bought a 5th line I could get it, so should have nothing to do with the iPHone, but should only have to do with the payoff of the Droid.

Does anyone have any suggestions on how to deal with verizon on this. I thought they would let you pay off the old phone based on months left.

Thanks.

Sadly, none are. I thougt about adding the fifth line and changing my daughters to that number and keeping the 4th till it runs out. Actually significantly cheaper than buying at cost the iPhone 5.