With regards using the economy 7 at night, if I am correct, you should check that other appliances are actually in the economy 7 fuse box. When I had it, every fuse in the Eco 7 box was taken up by storage heaters, and all other appliances etc (lights, sockets) were in the other fuse box, which I was told meant that they would never run on Eco 7. Not sure if this was true, but we ended up switching a few fuses about as some storage heaters were never used at all.