Undilivered item for 10 months

I bought bedroom suite from Ok Idutywa with my brothers account but I do payment every month. it took them 3 months to deliver and it was only bed, headboard and mirror I am still waiting for the chair. I send my brother each and everymonth to go there and ask them, they always say they dont know when it is going to be deliverd. I phoned the sales lady who helped me with the sale last year, her name is Ntosh, she sent me to the guy called Songezo, I ask him he told me that there is nothing he can do the chair is not there and he doesnt know where it is and hangs the phone. I phoned him again he was so rude to me telling he not involved with my issue and he laughed and hangs the phone again, I phoned and asked the manager, mangers phone was just ringing. I phoned Ok Furniture head office complaints department to report this issue. They said they will do follow up. Until now now I haven't received any feeddback. I payed deposit and paying full installment every month. I really dont know what to do.