Maaco Went in for paint to be buffed left with damage to door gresham Oregon

My son took my car to Maaco to have coffee buffed out and they quoted $50.00.  Then they charged my cc $75.00.  when my son brought my car home the coffee was not buffed out and the door had a noticable ding in it.  He said the staff appeared to be high and he could smell alcohol.  So I am stuck fixing a ding in the door that was not there and having the original issue fixed on top of damage they created.  They now deny doing anything and say that the door was already damaged before it got there.