Old Apartment I Used To Stay At Is Trying To Charge Me An Extra Month Of Rent?

Hello all, my old apartment tried to charge for an extra month of rent that I shouldn't owe according to our lease agreement. They tried to talk to me about it so I asked for documentation as proof that I owe them the extra 1800 but they were only able to provide a statement/the bill they sent to me. They said if I wasn't going to pay it that they were just gonna send it to collections and that I could handle it there. After it was sent to collections, I requested a dispute within the timeframe stipulated by the FCDPA, but they did not respond. I called and asked again for documentation as proof of the debt and the debt collector got hostile and just sent me a statement of the bill again without any legal documentation/contract. At first they claimed it was extra moving fees, but now they're claiming it was because I issued a stop on a payment in August and I still owe August rent. However, during my last month of rent (August), the leasing office charged my card twice so I had to stop the duplicate charge, but I have proof that I paid all my rent in full. Should I just reach out to a debt attorney and have them talk to the collectors for me?

Thank you for your help :)