Mazda,Brake lights on constantly

Hi I am having a frustrating problem with my Mazda 3. The brake lights stay on constantly when there is power to the battery. But when I pull the room fuse from under the bonnet they work as normal, however doing this stops anything from working on the inside of the car. I have changed the sensor on the wheel bearings/hubs, I have replaced the brake switch under the pedals. Replaced all the fuses both outside and inside, replaced the brake lights completely. What could this be? I am totally baffled

My car has 120000 miles.
My car has a manual transmission.