Complaint sub-issue: Debt is not yours

I was a tenant at one of XXXX XXXX XXXX XXXX from around XX/XX/XXXX through XX/XX/XXXX along with a co-tenant. My co-tenant and I had a disagreement resulting from the heat emanating from the basement from the landlords washer and dryer which resulted in mold growing on the walls and floor of the unit. The landlord refused to fix any of this, and mold did in fact grow on my furniture as a result. On XX/XX/XXXX the landlord suggested that if we wanted to get out of the unit, we were more than welcome with 30 days notice. The landlord offered this in writing via email and we tendered our notice via the same medium for departure on XX/XX/XXXX. In the interim the landlord sought and received my help to show the apartment to potential tenants, which he did receive. Based on this tendering we went ahead and signed a new lease with a new and different landlord. The landlord later changed his mind and threatened to sue us relating to the lease but it was too late as the landlord had let us of and we had signed another lease. Before we vacated the apartment, there were two issues that needed resolution. ( 1 ) whether the landlord wanted to keep upgrades we made to his unit specifically bathroom mirrors and a wardrobe, mainly aesthetics that lifted the face of the unit. The landlord was asked this question and did not give an answer either way. Except for a mirror and cabinet in the basement, I lost and trashed all my furniture and some clothes and shoes which had been riddled with mold from inadequate ventilation in the unit. The superintendent agreed to dispose of it and other pieces of furniture if the landlord did not want it after securing a new tenant ( I have this text in writing ) ( 2 ) Fixing a broken door which I had forced open to gain access to the backyard. The wood used to make the door was low quality because it expanded and contracted with heat making it difficult to open ( please see image attached of an initial request we had to the superintendent asking that he fix the door in XX/XX/XXXX. I had to force open the door around XX/XX/XXXX ). I communicated with the landlord that this, being the only damage in the apartment, as evidenced and confirmed via text ( I still have this text ) by his superintendent before the move out date, will be fixed before departure. I did not find a carpenter to make the repairs myself so I asked the superintendent to make and assessment and send me a bill if he would fix the door. We communicated via text message ( which I still have ), as was customary. The superintendent said it would cost {$250.00} to complete the repairs, including a new frame. I gave the superintendent {$300.00} to fix the door via a XXXX transfer. The superintended confirmed receipt via text but never sent me an email confirming receipt as requested ( I still have the text ). The {$300.00} including a {$50.00} tip since the superintendent agreed to throw out any trash and upgrades or furniture the landlord did not want ( as the landlord was actively showing the apartment to potential tenants ). Then in or around XX/XX/XXXX I received a message from the debt collector for rent calculated as rent for XX/XX/XXXX to XX/XX/XXXX. This, even though the landlord had asked us to vacate the lease in writing with a 30-day notice, which we duly gave. This, amount of {$17000.00} included interest costs and assorted damages. I disputed the debt with the debt collector stating that I did not owe any amounts under the terminated lease. I asked the landlord to prove the debt. This prove never came and instead a debt of {$17000.00} was placed on my credit report. This was not a court judgement, simply a self-assessment that did not account for the fact that we were asked to vacate the lease by the landlord and the superintendent confirmed no damages other than the door the superintendent was paid and tipped to fix. Furthermore, the landlord did not repay the security deposit of the co-tenant amounting to I believe ~ {$1800.00}. Indeed, landlords would usually use part of security deposit to clean the apartment in the case of any dirt left behind beyond typical wear and tear. Such cleaning would not cost that much, and repainting is considered wear and tear ( we did not repaint the unit from its original color ). The landlord is unfairly making this claim because they have the time and resources to do so.