If you need to free the valves to close them, take the top of the valve off, (sometimes they have a screw in the middle, perhaps under a cap, or they pull straight off with a tug) one will do, doesnt matter which, and get a small adjustable spanner, fit it nice and tight onto the brass spindle flats and then very gently move it from side to side, dont try to force it too far! you are aiming to get it to screw in clockwise, they are probably scaled up and once they start to move you will, by working them back and forth be able to screw them in and stop the flow of water to the upstairs. if in the process yo start to get water come up the shaft, DO NOT PANIC, the little nut around the bottom of the shaft is called the gland nut, it can be tightened to stop the flow of water but if you tighten it too much you will not be able to move the valve spindle, its best to tighten it just enough to stop the leak.
Have fun,
Derek, June 2004