Brand new broken phone refuse to repair

I baught a phone online which took ages to deliver. Once it was delivered I had it for 1 month and it broke. The home button randomly stopped working, voice control went on at random times (3 am) and then my phone would randomly call people or start playing music. Then the music stopped working completely. Then the touch screen stopped working. And the next thing the phone just switched off by itself and refused to come on again. I took it in for repairs. The staff at Foschini assured me that they will replace my phone, but I never heard from them again. After my 4th store visit, 3 weeks later they informed me that nothing has been done to fix my phone and that they won't replace or repair it because there's no waranty on the phone? I had it for 1 month and 5 days and I'm still paying for it every month? This is unacceptable.