please just give my money back!

I bought an Android TV Box in February. The TV Box is Android 6 software and I had to return it to Hifi Corporation Menlyn, who then sent it to the supplier because the TV Box did not have the Blue App store in it. Ultralink worked on the TV box, did a reset, checked the motherboard and installed the Blue App store aswell as apps like Netflix and DSTVnow. The box was returned to me, however it is still glitchy. Its keeps on saying that the apps Im trying to open is not responding I need to click on close the app or wait. When I watch DSTVnow, 2 minutes into a movie, the app restarts. I have reset this TV box I have tried everything. Bottom line is I bought a box that I am unable to use and Hifi corporation does not want to give my money back so I can buy a different box that I can actually use. I keep on having to drive to the store and the TV Box has to be sent in for repairs again. This is very frustrating!