ACDC poor product quality and returns process

I bought a sensor light PIR-N-20W-CW from the Silverlakes branch some weeks ago. It failed after a week. I took it back on a Friday. They said it needed to be checked and would call me the next Monday. Nothing happened ("It isn't back yet"), and more than 2 weeks later after I rattled their cage loudly and they replaced it with a PIR-N-10W-CW. When I opened the package and saw that it had clearly been installed before - the wires were indented and the mount scratched. This marvellous light works - but only when there is a light shining on it, never in the dark. Clearly someone has attempted a repair and connected the sensor electronics wrongly. C'mon, ACDC, you don't want your reputation spoiled like this. I'm done with repeated visits to your store and now expect you to deliver a working, tested PIR-N-20W to my home and collect the museum curiosity you supp**** to me. The staff in-store were friendly but hamstrung by a ridiculous returns process.