Overcharge of account

i bought a lounge suit in 2013 for R8 000-00. Up to date i already paid nearly R20 000-00 and still owing more than R4 000-00. If this account is settled it will cost me nearly R25 000-00. I was told that the insurance was compulsory although i said i have my own comprehensive insurance. I tried to talk to the manager about this account but i can get nowhere. It is really a ripoff to pay that much for an item where the selling price was only R8 000-00. i also want to warn people not to support this company as you will pay more than 3x the selling price.