Broken couch. No response

I bought a 3 piece leather lounge suite at House and Homes in Parow, on 6 June 2017. At the end of August 2017 the 3 seater couch was broken. On 1 September 2017, I emailed their repair department on the request of the sales lady. They just prepared the couch. Now, 6 months later, the same problem occurred. Now they don't give me any answers. I have bought the suite to last for years, but this only lasts for 9 months. I have requested that this particular set should be changed for another suite, and that I would pay in the difference. They refused. But they don't come back to me re this broken couch. I don't want this couches anymore Please help Mrs. N. Jansen