You might try Feliway cat appeasing pheromone
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=1061
You can also try holding Sandy on your lap near the cage area and pet and make a fuss of the friendly cat. Even use a spoon to feed Sandy a nice treat like some chicken baby food or a small amount of tuna.
Let Troy see you are not only not dangerous but might be nice.
I think expecting a change in 3 days is a bit optimistic particularly since he has had a month to practice being afraid of you. I'd count him as feral as he is not really used to human handling.
This article goes over feral kitten taming but may have some useful advice
http://www.feralcat.com/taming.html
more info here
http://www.for-the-love-of-cats.com/TameFeralCat.html
http://www.indyferal.org/index.php?page=tame1
See if the Feliway helps, discuss the possibility of a med to help calm him with your vet. It may be hard to find something you can get him to take though.
And work on patience as he's had two years before you and a month with you to believe that hissing and aggression is the way to respond to people.
Hope this helps you!
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