The radio tuner in a Highline saloon car is located under the cover marked B in the picture, it's the box on the right.
Lift cover marked A first, just pull it up with a bit of force, then unscrew the 4 phillips plastic clip fasteners on cover B beneath to lift that one off.
The radio tuner 17 pin BMW connector block can be seen in the next pic, (ignore the circled connector, it's not relevant to this post)
To remove the 17 pin connector block to check for corrosion, you'll need to put a flat bladed screwdriver in the slot at the top to slide the black plastic connector lock up then you can pull it off with a stiff tug.
If you need to remove the two small CD changer and Cassette / Sat Nav audio plugs, slide up the blue retaining clip first then they will drop out
