security

My wife has just got a Tino and they dealer seemed clueless said the code was in the book well no code plus it says in green and bold secure everything else works can not put a after market unit in as aircon is part of it will nissan still sort ? is there a way round this now and will it happen...

I have a Nissan Almera Tino that has a radio that doesn't work very often. You hear a sort of deep click as though it has come on and then the control panel lights up and you can then switch the radio or CD on and all is fine. Then another day you will go back to the car and all you get is green...