Poor client servive

I bought a LG Tallboy system from Makro. After months of running to and from they decided to replace it. At that time they had no stock so I was forced to opt for a Samsung and pay in a difference in price. Now I sitting with the same problem, I took the Samsung in and they send it out for repair, got it back with the same problem. I contacted Makro on Saturday 27 June and spoke to a lady manager who promised to call me back on Monday, needless to say today is Friday and no phone call. I do not want to take the unit back for repair again and I want Makro to replace it with a new one at no cost to me.