[ossiblue]

Deduction?

Cost of patch material + about 1 hour labor/time charge at their hourly rate (not counting the time it takes for paint/patch to dry) would be fair, IMO.

In all honesty, the patching might take 5 minutes, the sanding another 5 minutes, the priming and painting about two minutes--again, all this is actual working time, not allowing for drying or set-up/clean up. If you want to figure set-up and clean up, add another half-hour. Your call.

If the repair has a few complications, as mentioned above, then add time accordingly.

You might consider confronting them, when they return to finish, with your calculations based on the above suggestion and allow them to either accept the deduction or offer to repair it themselves, to your satisfaction. If you do make this offer and they want to do the repair, be sure it is written on the bill, initialed by you, and don't pay anything on the bill until it is done. The fact they never acknowledged the damage is a red flag that they may not be the most candid of professionals.