How is the law about home rental security deposit applied?

I moved out of a rental over a year ago. I had lived there for about 17 months. About 3 weeks after I moved out, I received a bill from the rental agency asking for nearly $5,000. This was on top of the $2,000 deposit that I had put down at move in. There were charges for things that were missing, or not clean when I had moved in. They charged for painting the walls, cleaning and replacing the carpet, and cleaning- twice. I had not completely unpacked, and there were boxes against the walls, so I don't understand how they would have gotten dirty. The carpet had not been cleaned when I moved in, and there were pine needles on the carpet from the prior tenants Christmas tree. Prior to my moving in, the cleaning lady had cleaned the place using a water bottle because she couldn't find the main water control. There were some things that were legitimate, but that should have been covered by the deposit. Now, I received a phone call from a collection agency. They wanted me to pay $4, over the phone, without seeing a bill, or explanation of charges. I requested that a copy of the expenses be mailed to me. I received only the dollar amount, with no description of the charges. I again requested a copy of the charges, and the accompanying invoices. I have not received this yet. What can I do at this point? It is way past the 21 days that they have to provide this information.