What a time you have been having Natasha :(. I don't live in the states so have no idea how exactly to help, but the things I would find out for sure: 1. Did they have any legal signs stating they could tow your car away after you parked it, even after the fire dept came? I don't know what a EPA is.
2. How do you really know it was towed by anyone, as maybe the attendant has kept the van and just wants to make a quick buck?
3. Can't you contact the police or solicitor because it's as if your car was stolen in a way? Or get some sort of advice
4. Are there any CCTV (closed circuit television) in the surrounding area that may be able to really show you what happened that night?
5. Contact the fire department to see if they really neutralised anything that night, maybe they did, maybe they didn't?
These are only guesses, hope it works out well for you. Hope the kids get well very soon, but I'm sure you're showing them with lots of love and mummy kisses :)