The question now is, how far are you prepared to go??
the responsibility lay with the painter. The painter cannot avoid this by giving you a discount unless, as weeal asks, the discount covers the cost of restoring the drive to its former glory.
In your shoes I would get a price to have your drive cleaned / coated. If there is a difference between the possible cost of this and the discount you should then ask the painter for the difference or that he(?) puts it right.
You also have recourse to the small claims court - that depends how far you want to go.