Have you looked on the Saxo forum of the Citroen Owners Club?

the heater in the car, all that unit not working apart from cd player which works?

You still have not answered the question,is the heater itself hot test by putting your hand behind the dashboard and feeling it if its cold lift the bonnet and feel the input heater hose is that cold.You need to test if the hot/cold valve is operating it may be jammed in the cold position in which case you need to take it out and replace it refill the cooling system with antifreeze and make sure its bled correctly.

If the heater is warm but the fan is not working then the chances are a blown fuse or a blown fan motor.