I remember all the peeling paint back a few years - think that was due to the switch over to waterborne paints and primers... I doubt that is your issue... but seems like you have enough "help" on the issue so far.
Might have been easier to get the dealer to fix it - but since the GM BK filing they might not be so easy to get warranty coverage on stuff that isn't "really" covered but "could be". Dealer probably doesn't need or want the hassle.
COMPLAINING COMPLAINING COMPLAINING!! Calling every person I could get a # for!! From local to regional to national. Finally my original dealer agreed to cover it. Not warranty it but pay for it out of pocket, works for me.