Please don't take this the wrong way iisfaq.
Just goes to show how important a Quarantine Tank is. Sure Animates should not have sold them, sure Brooklands should not have sent them. At the end of the day it is up to ourselves to decide what we put in our tanks.
Im sure you would not have brought them if they had looked like the photos you showed.
Whitespot can come on to healthy fish when they first get put into a new tank, i brought cardinals the same time (aquaday) and they had whitespot about 3 days later, 2 weeks went buy and it happened again to some otehr fish that were added, i really don't think this was the shops fault as it is common when new fish get added.
The other thing is that some of these nasty bugs take a bit of time to show up, and other are always present in the fish, just takes a slight change for the bug to come out.
I also find it interesting that the neons survived there 6 week Quarantine. When i worked importing fish we found we would get the odd tank (neons) with the diease you described and the fish in those tanks were all dead within 72 hours, furan 2 did not really work on this either.
Anyway hope it all works out im sure i also would be able to find the odd fish to get you going again.