It depends on how deep the scratches are but the firs tthing to do with small scratchs is fill them in with a wax crayon in the correct colour. This can hide a lot of scratches, and also stops the scratch filling with darker coloured dirt, which makes the scratch much more obvious. Regardless of anything else, I would do this quickly.
Apart from that, I dont know of any other possible repair other than a sand and varnish.
I would be complaining to the decorators to pay for the damage repair.