This switch had to be replaced as bathroom light downstairs was not coming on, switch on left was not working. One on right controls light on the stairs up top. When done the bathroom then worked, but not until bloke with screwdriver had left did I notice you could now no longer switch the stair light on then off upstair, if switched on upstair it would not switch off down stairs, so he's wired it up wrong somewhere. Now the one upstairs will not come on at all, not the bulb, and it was always flickering a bit after the new switch was put in. Bloke is not worth getting back, not a real electrician. Can anyone see an obvious fault in this wiring configuration?