Builders Warehouse - where the client is irrelevant.

Over a month ago my inverter stopped working, and upon checking the manual the sound it was putting out was evidence that it wasn't charging at all. Since I had bought the inverter through Builders Warehouse, and it was less than a year old and well inside warranty, I took it back and asked for a refund. The exceptionally unhelpful and distracted manager at the Constantiaberg branch said this was impossible and that they had to send it to the supplier to evaluate and then - as I started speaking - literally just walked off. So I booked it in - having no choice - and prepared for loadshedding! I have contacted Builders Warehouse on four occasions now, and they tell me they are waiting on the supplier to get back to them. I ask if they are actively doing anything to get supplier feedback - as they would need to give me the refund - and they say yes, they are waiting ;) I have asked them to please contact the supplier with due urgency and ask what is going on. I have asked them to please give me feedback, either way, as to what is going on, and yet have never heard from Builders Warehouse. Absolutely pathetic. I most certainly will not be shopping with them again, and especially not with large ticket items that might require returns. But... for now I remain at their uncaring mercy, as I need the refund money to purchase a new inverter.