WOW!!! first i am really sorry to hear about your loss....
second , try to get some Local intersted friends, any local govenment officals, other related ppl who might help put some heat on thier necks, to complain to the co-op, get them to start thinking they might loose a few customers to solar/wind power/ other co-ops whatever is available in your area, or possibly get investigated into for thier actions, maybe even your lfs can help out.... and try to calmly explain that yes a tank is a ecenomic value, you are purchasing a product from a local vendor which in turn pays his bills and possibly the co-ops... i know you really have to desensitize it but it might put it into perspective for the gentleman... ya know a doctor once suggested i spend more time in front of my tank because they are calming and i was suffering stress headaches
... maybe you could partialy pawn it off as a medical expense in that respect.... unfortunatly if you had to be escorted off the premesis the news thing might not help out that much anymore. but i have found out that a statwide 1 page add in every paper though expensive can really really get attention of higher ups to the point they might want to help... just remeber if you do letters use only facts not what you heard... if you can prove it with document video or voice tape it's not slander, but your walking on shakey ground, and you'll likely not be able to use thier services afterwards, just ask a local tire company on how well this worked. check your insurance, my renters insurance covers my pets (my fish and corals are pets right) it's not much, but it might help a little. lastly call animal planet there are a lot of ppl there who im sure would be very interested in the story.
hope this helps you out some