I rented an apartment from a company - when I moved out they claimed I had a balance due. They are incorrect and are trying now to collect on a balance that is not correct. I have paperwork proving otherwise. 

They have sent me to a debt collector - I 've told the debt collector I deny the debt - the debt collector has mailed me a " proof '' of the debt - nothing signed saying I agree to the debt - just a " bill '' for something that is incorrect. 

I 'm told I will need to hire a lawyer to even begin to fight these guys and they are suggesting they are going to start reporting me to the credit reporting things. 

What can I do to fight this without having to waste time and money going to court to prove something I 'm not responsible for?