CON5933

Any 'general builder' would be able to do it.... to be honest though, for a metre wide and 1.5cm deep i'd be more inclined to hire a slitter/grinder with the appropriate disc and a drill chisel..
criss cross the hump (like a big chess board) to the required depth and take it off with the chisel... (use water for cutting...coolant & dust..goggles and dust mask)

If your door frame goes right up to the lintel then as you said, dodgy builders or measurements to begin with..(or the wrong door frame in the 1st place) are you saying that there's no space for tiling up to the door because of no clearance? If so, I think you might just have to work around it. You could make it a semi circular feature with no tiles in the 'door sweep' just an inlaid mat?