Faulty inverter and no feedback

After purchasing an inverter in February, we noticed it was faulty and returned it to the centurion branch the next week to replace it with a new one. We were advised that they will take it to the manufacturer and replace it. We only got the ‘news‘ inverter back in July after we had to keep calling for feedback in a much worst state. As soon as we plugged in the ‘new inverter’, it started tripping the main switch so we took it back to the centurion branch which was 3 weeks ago and Ezekiel advised that he will provide feedback with 2 days which didn’t happen and he is now avoiding my calls and when I called the store their best solution is to call the manufacturer directly. Why must the customer call the manufacturer when the purchase was made at makro and if you can’t replace the inverter with a NEW one, when can the refund be made