1) Make a complaint in writing and mail it signed return receipt (to prove it was sent and received).
-Make it short, specific as to the details (when, what, how, who, where), and make references to any violations or applicable sections of the written work contract regarding damages to property.
-Avoid emotions, threats, etc. while writing it. It may be seen by a small claims judge or mediator so make is sound like it was written by a lawyer (they like such things).
2) Take pictures. Use a artificial light at an angle with a tape measure next to each significant damage. The angled light will let the damage show better and the tape measure will document the size.
3) Get 3 quotes of what it would cost to repair the floor; obviously not from the guy who damaged them.
4) Be careful about what you do or do not pay the contractor. Don't pay for the flooring (if you haven't already).
-You might want to put all money normally due the contractor in a separate bank acct. This will show a judge/mediator that you're not just trying to avoid paying or trying to renegotiate contracted costs.
5) After you have done #1-4 above, negotiate with the contractor re: repairing the floor (if possible...laminate floors or floors with a thin wear layer can't be repaired or repaired and still be worth their original new value).