Complaint sub-issue: Debt is not yours

My fiance and I rented a place in XX/XX/XXXX, and signed a year lease. Within the lease it stated we would be able to break the lease without repercussions if a 30 day notice is given of wanting to leave the premises. We gave the manager a 30+ day notice that we had found a house to rent and wanted to leave the lease agreement, via Email and written notice. In the Email I gave information with how to contact us if any further correspondence would be sent from them after we left the premises, which was XX/XX/XXXX. Nobody from the rental management/company had contacted us after we left the premises about anything, or any possible debts owed, even though they had our information to contact us. After receiving no correspondence or notification of any issues, we continued on with our lives. However, in XX/XX/XXXX a collection for {$7600.00} was reported on our credit reports from a debt collector, with the original creditor being " XXXX XXXX XXXX '', the place we rented from and left in XX/XX/XXXX, which we discovered in XX/XX/XXXX. I immediately contacted the debt collector to find out how we could owe a debt of this sum. She stated the creditor sent the collection to them and stated there was approximately {$4500.00} due in rent for " breaking the lease without notification '', although they received notification, by email, and responded they received it, as well as written notification. and approx. {$3000.00} in damages. However, we were NEVER notified of any damages, and it stated the carpet had to be replaced, trim replaced and cabinets fixed, ( most due to pet damages ). We didn't have any pets, so we didn't cause the damage by pets, and we had notified them upon renting that there was multiple areas of chewed/damaged trim and one of the cabinets needed to be fixed. Also, there was a horrible cat urine stench coming from the carpet, and areas it was falling apart from prior tenants and needing to be replaced. We had notified them about the issues with the carpeting and the only resolution they offered was to use an " ozone machine '' which we didn't feel comfortable with because they cause high levels of carbon monoxide, and are dangerous to use, and would only eliminate the odor for a couple weeks. We sent them pictures of the carpet, and they stated we could pay ourselves to replace it, and since we were just renting we didn't want to spend our own money on it. I told the debt collector this is NOT a valid debt, and everything that happened, and she stated I could dispute with the credit bureaus. I disputed with all 3 bureaus for my fiance and myself, submitting all documentation. The account was deleted from all 3 bureaus on my fiances end, and XXXX and XXXX deleted them from my report. However, XXXX will not remove this invalid debt from my credit report, despite multiple attempts to dispute with all documentation provided, and notifying them all other credit bureaus have deleted the account. The debt collector also stopped contacting me, until recently. They are still trying to pursue the debt, calling multiple times a day, and sent letters stating if we don't pay the amount they will " damage our credit '', and try and sue us in court. I have tried everything to get this removed from my XXXX report, and it will not be removed.