Zulteck won'treplace defective Inverter

We bought (and paid for) Batteries and Inverter (R15070) in April 2015. It was meant to give power to our home during load shedding. The goods were dilivered but the Inverter was faulty. Zulteck blamed the electrician and after a long standoff lasting many weeks, Zulteck grudgingly accepted that the machine was broken to begin with. On telephonic enquiry nobody wanted to take responsibility for this unacceptable situation. Eventually about two weeks ago they promised to deliver a new Inverter the next day. Up to now, 13 August 2015, it has not materialised. We phoned again and was told that the driver was sick or something. We have accepted by now that we will not get a refund or replacement without legal aid.