It's really easy to get the cd's out, just a bit of patience and and a small screwdriver. mine did the 'dreaded err3' I took the cd's out and 6months down the line Iv'e had no problems.
lift up and unclip the felt pad above the centre air vents
undo the 2x 10mm bolts
pull firmly the air vents out.
undo the two 10mm bolts that were under there
pul the heater switches out from underneath sliding towards you
undo the 2x 10mm bolts that were behind them
NOW V IMPORTANT, MASKING TAPE up either side the air con unit and the stereo on the dash
lift the stereo and air con out carefully as to not damage the dash
unclip the connectors from the back
undo the the stereo from the side brackets (again bolts and I think they were 10mm if i remember right, about 6 in total) and take off
you will need a small posidrive screw driver
I think there is 2 small screws in the back and side to undo the top metal cover
there is a sring mecanism that clamps the cd trays down, its two springs, one from each side of the metal bar and the go down the side and fold in along the bottom and join together in the middle under the cd's, it is not a problem if it pings out because it is very easy to re-connect, you will have to unconnect one side and try not to let it undo then you will be able to acces the cd's, just flex them and they should just pull out, you may need to cut them out (depending wich tray it's in and where the lazer has stopped) just use some scissors, (£10 cd is cheaper than £500 stereo)
reverse process and put back in car, toggle through the empty cd's and the err3 should dissapear and the display that tells you what cd slots are full dissapear.
Did exactly this today and it was a pain in the bottome. Cleared the problem. Will only be using single cd at a time from now on.
Want to keep the OEM stereo and look for the resale.