The valve has two controls. Firstly the control that controls the heat is stuck and will not turn. Secondly I can losen the cover plate, but can't seem to get the controls off. No allen key holes or anything. Seem like they should just pull off. Taps are about 4 years old, customer complained that they can't control the heat anymore. How do I get the controls off? Can this be serviced and how? Should it just be replaced. Can't make out the make. It has got a sign on the cover plate with the letters IB in oval circle. Could be LB too? Please any advise will be great.