I have been buying a few parts here and there and I have experienced the same issues as all of you. There has been some comments on here that Holden were the place to go for some parts.
The bushes/regulator unit on my alternator needed replacing so I went to holden. They needed a VIN (I am like, I don't have it with me, the car isn't working which is why I need the part)and told me there were 2 different alternators and needed to know the correct one. At this point I am thinking this is just too hard, will try somewhere else.
I then went to Autopro in phillip (in the ACT) and within 5 min I had the part in my hand as well as some info about how to install it. I have been back to these guys a few times for oil/filter, battery, thermostat and gasket and a few other things and they win on price and service. Anyone reading who is in the ACT I recommend them.
There is also a chick on the counter and within 5 seconds I knew that she knew her stuff and had been trained by the guys at the shop. It makes such a difference when you get great service by people who know what they are doing.
I have used Repco a fair bit and their tools are excellent, have not had one fail yet. They are a little bit more expensive for other stuff than the supercheap/autobahn.
Another Story
I went looking for a light bulb for my ef falcon and was after the right one. There was no spare parts book near the globe rack so I asked the parts guy. He said he didn't know and didn't bother to look it up for me. I went across the driveway to supercheap and had the part in 5 min.
I then went back across to autobahn and a different guy was at the counter and told me everything I wanted to know and was a pleasure to deal with. So even in the same store it can be different.