Hello amy:
You keep asking for the law, but when our resident real estate LAWYER asked you the question that the law HINGES upon, you didn't answer...
The KEY (depending on your answer to Lisa's question), is the TIME frame. It's NOT the bannister... It's NOT your son. It's NOT whether it was secured.. It's NOT whether he did it on purpose.. It's NOT ANY of those things...
It IS whether they informed you WITHIN 21 days. That's IT. If they informed you WITHIN 21 days, the issue is about damage, costs, etc.. But, if they informed you a MONTH after you vacated, then the only issue is that it took a MONTH.
IF that is the case here, sue for your deposit back in small claims court. You'll win.
excon