My nephew dry walled my dining room by just screwing into the concrete wall. He did not put anything under it. I did not know this until he was finished with the job. Needless to say, it was a horrible job! I want to add that I really did not get to angry with him even though he told me he knew how to dry wall. I have no idea what the walls look like underneath it all. What can I do now? Any suggestions? Thank you.