Best advice? Avoid the GSP like the plague.
My buying options have become more limited since sellers I used to buy from signed on to the GSP, but as your post has demonstrated, it's better to do without than to pay the money for abysmal service and damaged goods.
Sigh. If only eBay actually cared about its sellers and buyers, but it's clear they couldn't give a rats. Imagine how much better things would be if they did (....and how much more money they would probably make).
It's not rocket science.
