omg that sucks donkey rear! hugs for your loss!!
I'd get back onto the insurance company, it WAS stolen, just becuase the police recovered it before you found out is neither here nor there. check out trading standards in you area and email them with your problem.
check if equity red star's (that's who i'm with

might bump them and tell them why) paper work says anything about their theft policy on it etc. if it doesn't tell you what they said then they shouldn't be dismissing your claim.
they shouldn't have that as a company policy anyway, as an owner could have a car stolen while they're on holiday etc, and woud have to claim retrospectively. if the lackey at the insurance company doesn't give you any extra info, speak to their supervisor, if they're as bad ask for the department manager.
Trading standards should be able to give you some info at least on what you can do and say to get what you're entitled to. ask the coppers as well next time you see them, they'll probably have had something similar before.
good luck mate, hope you get to kick the thieves in the nuts as compensation. you could always go 'american' and sue them for damages, compensation and emotional distress.
if/when you get your car back, get a steering wheel lock for it.