pjs

Recently bought a Citroen C3 SX 53 plate via private sale. The switches for the aircon, recirculation and rear demister do not light when pushed and there is no function. I have looked at the glove fuse box and fuse 10 (40A) appears to be OK. (Fixed the wing mirror adjustment by changing the fuse and hoped this problem would be as simple) The car does have a replacement radio/CD fitted; this may or may not be relevant. Anyone have similar experience and/or know what the problem is likely to be and how to fix it? Is there likely to be an earthing problem? Thanks for any assistance.