To take out the radio, you will have to remove the element with the heater and a/c controls in it first. This is fastened with two clips on the sides:
1. take an old creditcard (or something similar) and bend one (short) side of it in a 90 degrees angle.
2. insert the card between the radio and the a/c-controls, bend side first.
3. move the card to the upper/side of the a/c-controls and pull it, making sure its bend side hooks behind the controls.
4. the a/c control unit should move forward a bit. Repeat step 3 for both left and right side.
5. you should now be able to pull the a/c controls forward.
Then you can remove the radio:
use a screwdriver to remove the two screws beneath the radio and pull the radio forward.
Some pictures to clarify the way the A/c controles are snapped in:
left side:
Right side:
Bottom of a/c control panel:
Panel removed:
Back side of panel:
Where the panel came from (screws of radio are visible):
Back side of the radio: