Had the same problem myself, finally solved by removing a small screw from each side of the radio. The problem is these are located behind the trim but still very close to the front of the radio, I had to lie on my back with my head in each footwell in turn and reaching up the side of the radio into the dash removed them with a crancked screwdriver and lots of swearing! .
Why struggle when all you have to do is take out 5 crossheaded screws out 4 in speedo trim 2 top 2 bottom and 1 in deep recess in cubby hole past heater switches
then pull carefully by hand the plastic facia as far as you can
reaching in pull off security wire fixing and heater wire connection block
this will give you room to get to the fixing screws on both sides of radio
then you can pull out and guide it out to disconnect radio
i did this recently to my 02 plate matiz and it worked for me
replace wires in holders gently with palm of hand locate facia into position and replace screws no swearing just a little gentle brute force needed