2002 vw jetta stereo

I have a 2002 VW Jetta GLS. I picked up a Pioneer DEH-790BT and had it professionally installed on the 18th. Unfortunately, it didn't seem to be wired correctly (no constant power) because all of my settings would disappear every time the car was shut off. Also, after I turn the car off and take out my key, when I open the driver's side door, I'll get the "headlights on/engine on" chime for a few seconds even though the headlights are off and the key is out of the ignition. After a few seconds, the chiming will stop and I know that the power to the stereo has gone completely out. I'm guessing this has something to do with the switched power/constant power wiring. I took the car back to the installer yesterday (the 21st) and he said that he switched the two wires, but I'm having the same problem. I'm going back to the installer today (the 22nd) but would like to have a solution that I can bring to him to get this taken care of once and for all. Before having this stereo installed, I had another Pioneer aftermarket stereo installed and had no problems with it (DEH-P7400MP). Any help will be greatly appreciated. Thanks!

sedate wrote: You could try running a dedicated power/ground with 10 or 12 gauge speaker wire directly to the battery/grounding point - then disconnect power/ground from the wiring harness leaving only the acc connected.

The installer mentioned that yesterday, but didn't do it. I'll mention it to him when I see him today. Any other help will be appreciated. Thanks!