Product: Debt collection

In XXXX XXXX I moved from XXXX XXXX, XXXX to an apartment complex, XXXX of XXXX XXXX, in XXXX, XXXX. The apartment I originally rented on the phone directly with the complex manager was a downstairs XXXXbedroom, XXXX bath apartment. When I arrived at the apartment complex with my moving van the only apartment that was available was on the fourth floor, with only outside stairs and no elevator. With my moving company being paid by the hour, I agreed to take the apartment. Within the first couple of days I found out the air conditioner did not work, the freezer and ice maker was not working, the plumbing had problems, and all of the windows in the apartment had been painted shut and could not be opened. The complex was going through a change in management and had only XXXX maintenance person, who was lacking in experience. I was promised everything would be fixed, but 2 months later in the hottest part of the year in the South, I still had no air conditioner, my windows still could not be opened and my plumbing still had issues. The complex finally agreed to let me out of my lease and I moved out on XXXX XXXX, XXXX after living in the apartment for only 2 months. The day of my move I returned the keys and my final check to the complex office, to a temporary employee, who was the only person available. This temporary employee could not give me an accurate accounting of what I owed as a final electric bill. I left them with my forwarding address and current cell phone number. 

XX/XX/XXXX I received a call from NCC Business Services , Inc. stating that I was delinquent on a bill to XXXX XXXX XXXX apartment complex. They could not tell me what it was for, just that I owed {$100.00}. I called the XXXX XXXX XXXX office and found out it was for my final electric, sewer, water bill for the month of XXXX XXXX. The complex would not take my money but required me to pay through the Collection Agency. On XXXX XXXX, XXXX I called NCC Business Services, Inc and paid, directly from my deposit account, the amount due of {$100.00} over the phone. 
Then a year later, XX/XX/XXXX I received a call from NCC stating that I owed them {$100.00} for a delinquent account with XXXX XXXX XXXX. I have had nothing to do with XXXX XXXX XXXX since XXXX XXXX when I moved out. Again NCC could not tell me what the amount was for or what time period it covered. After several calls from NCC trying to bully me into paying this amount immediately, I looked up my XXXX XXXX bank statement and it did, in fact, reflect payment to NCC Business Services, Inc on XXXX XXXX, XXXX in the amount of {$100.00}. I forwarded this information to NCC and their comment was that this could not possibly be the same charge and that I could either pay the amount owed immediately or the debt would be reported to the credit reporting agency. I do not owe this amount, it has been paid in full for over a year. They can not produce any documentation regarding this amount they say I owe. I called XXXX XXXX XXXX and they do not show that I have a past due balance. 
I have no idea what to do at this point. 

I could not upload a copy of my bank statement reflecting payment, but I do have a copy I can provide if requested