I have the full can controls (with rollers) on my steering wheel, the lower button on the left hand side has stopped working.

This button is used to switch between the radio and cd playback. I have a brand new spare set of buttons lying around my garage [as you do] and have tried them and they made no difference. So the problem lies elsewhere, but where?

I have plugged in my laptop and checked for codes and apart from it telling me my OSR door speaker was not working i did not have any other ICE or CIM errors..

This is a PITA, any ideas?