If it's the bottom of the door, you could try the old rough sandpaper on the cill trick and opening and closing the door a few times. Then wax the area that's binding.
The tool the carpet fitter may have used might be a biscuit cutter. Very rough if so.
A biscuit joiner will only cut to a depth of only about 22mm. I don't see why you think a biscuit joiner was used.