You're going to have to get brutal - use a hammer and chisel or something to bash out the broken off torx bit then drill the heads off the siezed screws. The screws themselves should drill out easy, then you might find the spacers themselves are stuck to the brake disc, so you might have to get brutal again. You might be able to take the old disc off with the spacer still on and then have a go at removing the spacer. Heat will probably help, if you can.
When you put it back together, smear copperslip anti sieze on all revelant surfaces. Also, try filing a couple of angled slots at 180deg to each other on the back face of the spacers, so that next time they need to come off you can stick an old flat blade screwdriver in the gap and bash it with a hammer - this will pop the spacer off with no drama.