Product: Debt collection

We had rented an apartment and moved with our newborn baby in XXXX XXXX XXXXXXXX XXXX XXXX XXXX XXXX XXXX, NY XXXX on XX/XX/XXXX. As we settled in, we start facing uninhabitable and hazardous conditions in apartment. The apartment was infested with spiders and other bugs, and it became nightmare to live in as we will find bugs crawling everywhere in our bedroom and living room space. We never had peaceful sleep because of dogs barking in the hallway, and right outside our bedroom window. As adults we often tried to ignore noise from barking dogs but it impacted sleep of our newborn daughter. The barking from dogs would often startle her, and she kept waking up during the day and at night. 
We informed the building management multiple times about these problems, and they would give us lip service that will either move us to new apartment or try find a solution. 
While we were struggles with all these nuisances on daily basis, a fire broke out in an apartment on the top floor of the building on Sunday XXXX, XXXX. The fire was contained by fire department but the water from the top floor apartment leaked through the pipes into our apartment on first floor and flooded our closets and damaged our furniture and other household items. With fire departments effort, fire was controlled but the damage done to the apartment was severe. After the flooding, six blowers and three industrial dehumidifiers were pressed to service in this 1000 sq ft. apartment. 
Altogether the noise and pollution were beyond tolerable limits. The blowers wiring was all over the place and we could not put our XXXX-month-old daughter down for a single minute. Two days after the flooding, on XXXX XX/XX/XXXX our daughter got sick and started throwing up. Signs of XXXX rashes appeared on her body. We had to rush her to the hospital and after a lot of back and forth to the hospital, her health has not been stable since then. Though she was admitted to the ICU to control the XXXX, her health has not been stable or normal till now. The doctors advised us to relocate the baby elsewhere for her recovery as staying in this apartment will be detrimental to her health with devastating effects for a long time. 
Living in the flooded apartment with the noise of the blowers and humidifiers and spending weeks while the apartment was being repaired really took a toll on the health of our entire family. Under the circumstances we were advised by our lawyer to inform the management that they are in a process of relocating themselves. We informed the management company via email that we will be moving out of our apartment ( XXXX ) on Friday, XXXX. The management companys response was so heartless that they asked us to stay because our lease period was not up. So, we asked our lawyer to send the management company a letter explain our situation and inform them that we also reserve our rights for any damage claims. 

Instead to contacting us to discuss how to resolve the lease issue without informing us they have reported us to a debit collection agency on XX/XX/XXXX. We received a letter from the debit collection agency stating that we owe {$18000.00}. Because of this claim our credit scores have been damaged. 

We dont owe them anything. We have paid all our rent while we stayed in apartment. We request through this agency that they should cancel this false claim that we owe them unpaid rent.