Nightmare couch!!!!

I have been a victim and i dont know who to turn to for assistance. I bought a couch on account with this funiture store for R20 000 late last year. When the couch was delivered i noticed that a part of the couch was sagging when the head office called me to do a routine customer satisfaction phone call i reported it. It has been with me till today. I have no problem with paying my account but i feel that i am being victimized. This matter has been dragging for more than 6 months. I am stuck with a sagging couch and yet im expected to pay an installment. I have been going back and forth with the head office and the store. I am desparate for help!