If you are being charged for normal wear and tear and you can prove the conditions of the unit upon move out, you could challenge the failure to return your deposit by writing a letter demanding the deposit be returned and/or filing a small claims case in DC Superior Court. The DC Small Claims Recource Center or Landlord Tenant Resource Center may be able to help you fill out the paperwork. If you can resolve it with the management company without going to court that will likely be less time consuming. You can also demand proof of the costs of the repairs. If you do nothing the company could try to send this "debt" to a collections agency and it will be easier to deal with before that happens.