Hi, I had the same annoying creak coming from the general area of the left side dash speaker.
Thinking that the creak was coming from the speaker cover I removed it several times, tried padding it with felt and other materials but nothing worked. The last
time I removed the speaker itself which is held with two hex bolts and was suprised to find the famous White Clip directly below the speaker. (I thought it could only be accessed by removing the dash). By pressing lightly on the white plastic clip I found that I could exactly reproduce the annoying creak. I sprayed the white plastic clip with silicone, pressed it again and the creak had gone.
Don't know how long the silicone will last but at present the car is creak free.
With the speaker removed I also noticed that there were two plastic heater
pipes which were running very tight to each other so I sprayed them as well and wedged
a small piece of sponge between them, just in case they decide to join in the chorus.
