Wow, really sorry to hear about your experience.

I can report that I've had both a bad and good experience with zoafrag.com. A couple months ago I placed a large order, large enough to meet free shipping requirements. After acclimating in my tank, my zoas developed the white-ish covering as well and many came detached from the frags they were glued to. About half of my order died off within days. (bad)

I contacted John, explained my situation and disappointment but did not ask for a refund of any kind. Much to my surprise he responded quickly and told me that he would replace the ones that had died off. It took some time, but I did receive replacements and most survived after acclimation. (good)