Morgan Properties review: move out charges

My lease was scheduled for renewal on October 16 2018. I informed the complex that I was in the process of closing on a new home and was unsure how long I would need to renew. The person that answered the phone stated no problem, just let us know when you have a date. Call back when the date was determined and proceeded as instructed. Later I received a notice that I owe 4086 dollars, made several calls to the leasing office, promised a return call to no avail. Matter was sent to collections where the representative was not eager to assist. Tried calling the corporate office and received no answer. I went to voice nail and was unable to leave a message because the mailbox was full. Til this date, the fee is recorded on my credit report and I am unable to resolve the matter with the company because you can get to a live representative.