Reading the responses I find the same questions turn up. Michael B and others have been dealing with this issue for years.

Here are some summaries which should be useful: http://www.dpi.vic.gov.au/agricultur...eekeeping-pest

and

http://www.dpi.vic.gov.au/agricultur...eekeeping-pest

I live near the epicenter of SHB investation in Australia and while we all wish they had never arrived, it is possible to keep bees even here.
I change my traps ( I found the ones from MannLake and using DE most successful) every 3 weeks during the season - when the weather is warm and humid. I just about always see at least a few SHB when I open a hive but losses like the one shown above is a very rare event.
Don't give up - try again.