My C5 LH turn signal stopped working. How can I access light to replace bulb? Also how do I remove the LH door trim panel to access door lock button? The unlock button works, so do the RH door buttons and remote. I think it can be fixed if I can get at it. The dealer wants $100 just to say Good Morning!

 

As for the turn signal bulb, you could either go in from underneath, (thats what i did) or remove the headlight assembly and get to it that way. I haven't tried this but from reading here in the forums it's rather a simple procedure.
If you choose to go in from the bottom, just remove the plastic panel, just a few screws and it comes off pretty easily. If you dont mind laying on your back and working from there, it should take about 20 minutes or so.

Not sure about your door panel, but I'm sure it just pops off. Pry from in between at the fastener points, they do make a door panel removal tool for this, of course I could be completely wrong here also.