Bad/Poor Service delivery

I opened an account and took two(2) items on account, a bed and 3-piece wall unit. On Delivery the wall unit was faulty so I told the delivery guy to take it back, but he said that he couldn't I have to call the sales person and report it. I reported to the sales person and manager several times. It took them about four(4) months to collect the wall unit. It was never used since delivery. Last month I went to pay my monthly payment and I am in arrears, because I'm supposed to pay the full payment wall unit and bed. How am I suppose to pay something I don't have or ever used? At the moment I'm marked as a slow payer on their system, which isn't good, since I'm still young and could affect my chances on getting other accounts. I notified customer care as well, they phoned me, but nothing has happened since.